This manual is intended to be a comprehensive one-stop guide to playing Kerbal Space Program. It will include an overview of topics and mechanics, and have links to other relevant pages on this wiki that provide more detailed information on each subject. This manual is NOT a walkthrough, but it will provide the fundamentals needed to play KSP in its entirety.
- 1 Associated reading
- 2 Menu System
- 3 Game Modes
- 4 Kerbal Space Center
- 5 Basic Vehicle Construction
- 5.1 Using the VAB/SPH Controls
- 5.2 Vertical Rockets
- 5.3 Horizontal Rockets
- 5.4 Not Rockets
- 5.5 Setting Action Groups
- 5.6 Crew Placement
- 6 What Can I Do?
- 7 Advanced Vehicle Construction
- 8 How To Fly Your Rocket
- 8.1 Escape Menu
- 8.2 Quicksave
- 8.3 HUD
- 8.4 Part Interaction
- 8.5 Navball
- 8.6 Launch
- 8.7 Landing
- 8.8 Flying Aircraft
- 8.9 Flying Spaceplanes
- 8.10 Maneuver Nodes
- 8.11 Orbital Transfers
- 8.12 Advanced Orbital Maneuvers
- 9 Outdated Information
There are a few other articles that may aid understanding of this manual.
- Read through the controls — these will also be linked to for every new aspect of gameplay.
- The FAQ and the Getting Started guide can answer technical problems (including installing the game) that may not be covered in this manual.
- Complex terms will be defined within this article for context and understanding, however the terminology page contains more details.
- If you simply want to launch something, do this "walkthrough to launching your first rocket", and then come back to this manual.
The game's main menu presents you with the options to Start Game, adjust the in-game settings, visit the KSP Community website, visit Curseforge — a community driven mod site (replaces SpacePort), view the game's credits or quit and return to the desktop. Additionally, you are also able to Check for Updates to your game.
The game's current version is displayed in the bottom right corner.
After clicking Start Game, you are presented with the ability to Resume a previously Saved game, start a New game, play through one of the games tutorials, or enjoy a pre-defined scenario.
- Career — complete contracts to earn funds and reputation, and collect science to unlock parts.
- Science — collect science to unlock parts, without the financial restrictions of career mode.
- Sandbox — build freely with no restrictions whatsoever.
Kerbal Space Center
Whenever you first open a game in Kerbal Space Program, you will be taken to the Kerbal Space Center (KSC) scene. From here, you can highlight the structures by hovering your mouse over them to see a description, and can access them by clicking on them. Each building serves a unique purpose, and not all are accessible in every game mode.
- Vehicle Assembly Building (VAB) — this is where you build vertical vehicles using radial symmetry (rockets).
- Spaceplane Hangar (SPH) — this is where you build horizontal vehicles using bilateral symmetry (spaceplanes).
- Launch Pad — this is where vehicles from the VAB are launched. You can also launch here without going through the VAB.
- Runway — this is where vehicles from the SPH are launched. You can also launch here without going through the SPH.
- Tracking Station — this is where you can observe orbits and access previously launched craft.
- Astronaut Complex — this is where you can hire new kerbals into your space program, and see the status of your astronauts.
- Research and Development — this is where you can research new parts in exchange for science (not available in Sandbox mode).
- Mission Control — this is where you can view and accept contracts (not available in Science or Sandbox modes).
- Flag Pole — in front of the Astronaut Complex, this is where you can change your default flag.
When in career mode, you current funds, reputation, and science are displayed in the top center bar. In science mode, your current science is shown there. In sandbox, only the date/time and time warp controls are displayed.
Basic Vehicle Construction
The Vehicle Assembly Building (VAB) is where you can build vertical vehicles using radial symmetry, and the Space Plane Hanger (SPH) is used to build horizontal vehicles using bilateral symmetry. The basic mechanics of building vehicles are the same for each building, and you have the same parts available for both; but due to the orientation you use, they tend towards differing styles of vehicles (VAB for Rockets, SPH for Spaceplanes). If you are reading through this guide with only the demo version, you will not have the SPH available to you, nor many other features offered within the game.
When building any vehicle, you will first have to select a root part (note that not all parts are allowed to be root parts). This part can be changed with the Root tool. Generally this part is a command module in order to provide "control" for the craft — control is only given by command modules, and without it you cannot make the craft do anything (it ignores your commands and continues doing exactly what it was doing previously). There are two primary considerations when choosing a command module: 1) do you want a one man crew, a three man crew, or a probe core, and 2) how large (diameter will generally be referred to as the "size" or "radial size" of a part) do you want the module to be. It should be noted that only a part's displayed mass and lift properties (you can right click on a part to see more information) affect aerodynamic performance, therefore how "streamlined" the craft is tends to be irrelevant.
Using the VAB/SPH Controls
The first part is placed simply by clicking on it in the left side panel, but each later part must be manually placed by selecting it from the side panel, then moving it to where you want to place it and clicking again. You can drag any part by clicking, releasing, moving the mouse, then clicking and releasing again (all parts attached to a part will move with it). All interactions are done via a single click — there is NEVER any reason to hold ANY mouse button down, except to move the camera. If you have a part selected, you can rotate it with the QWEASD keys, or delete it with the delete key or by clicking anywhere in the parts list. Most parts connect to the top or bottom of your rocket (or front or back in SPH) via nodes. These nodes appear as green balls when you have a part selected, and their size indicates their connection strength. It takes two and only two nodes to create a connection, and selected parts with nodes will snap to a nearby node if it is available. Additionally, some parts can be mounted radially on the sides of your rocket (without using nodes) in addition to being stack-mountable using nodes. This is where symmetry controls and angle snap come into play (as explained in Tutorial:Basic Rocket Design). Some parts can only be surface mounted/ radially attached, such as parachutes. If a part you have selected is glowing green, it is ok to place it there. If it is glowing red, you cannot place it there, because either there is no node to attach it to (if it requires nodes), or it is currently "clipping" (colliding) with a previously placed part. If symmetry is on, one un-placeable part will prevent the placement of all of the parts you are trying to pattern.
Parts are divided into categories based on purpose (command, propulsion, etc), and you can access the different categories by clicking on the icons in the top left corner of the VAB or SPH to switch between tabs. Depending on your screen resolution and size, there may be multiple pages for each tab, which can be switched between using the double arrow buttons on the bottom of the parts tab.
There are also 3 blue buttons at the top center/left. The first is "construction mode", where you can place, move, modify, and delete parts. The second is "action group mode", where you can set your 1-0 keys to perform specific actions. The third is "crew placement mode", where you can choose which kerbals go where.
In the top center of the screen is the name of your craft, which can be edited by clicking on it and typing. Further right are the new, load, save, launch, and exit buttons. These would seem self explanatory. Be careful to save often however, as KSP will NOT warn you if you are about to leave your current unsaved vessel.
This will provide a fundamental guide for building any rocket.
- For instructions on how to use the VAB placement assists, such as angle snap and symmetry.
- For a walkthrough on building and flying your first rocket — Tutorial: Walkthrough for Ye Compleat Beginner.
- Also review the VAB/SPH controls and the VAB page, as their information is necessary to build a rocket.
The VAB is where you will generally build the traditional vertically launched rockets and shuttles. For most rockets, you should start with a command module. To make space for the rest of the rocket, you can drag the part up high. You will want to add sufficient parachutes to the top or sides, as this is the preferred method of landing on planets and moons possessing atmospheres (with the partial exception of Duna). Commonly, a docking port is placed on the top of the command module to facilitate docking, causing radial parachutes to be necessary. A decoupler is usually placed beneath the pod, as this allows you to detach the command module from the rest of the orbital section during/prior to re-entry, therefore reducing the amount of parachutes needed for a safe landing.
The next section to build is the Orbital Section. This will typically fill the role of a service module, and many end up looking like an Apollo CSM. This section will have a fuel tank paired with a high ISP ("fuel efficiency") engine. It will also commonly have batteries to store electric charge, and solar panels or RTG's to generate electric charge. RCS (reaction control systems), including thrusters and monopropellant tanks, is sometimes added to this section to facilitate docking. Command modules typically contain small amounts of electric charge and monopropellant. Lights are typically only added if planning to land on the dark side of a body (or dock in a shadow), since space has enough ambient light to be able to see the status of your craft otherwise. The ideal arrangements of these components will be covered in Advanced Vehicle Construction.
Building a Launcher
Next you need a way to blast this 'orbiter' into space — this will be known as the Launcher. When you develop a reliable launcher, you should save it as a Sub-Assembly in order to be able to easily use it again. Start by placing a decoupler beneath the engine of the orbital section. Now you need to decide how many stages you want your launcher to have. Generally, a 2-stage launcher is the most efficient way to place your payload (orbital section + command module) into orbit. Having more than 3 stages in your launcher makes it very fuel-inefficient, and results in a much larger rocket than necessary — this creates more opportunities for things to go wrong (explosions), and in career mode makes the rocket prohibitively expensive. Also, the heavier a rocket is, the more fuel is needed to lift it — that fuel is heavy too, producing a loop of diminishing returns. These problems combine to explain why 'moar boosters' is not a good thing (though it is amusing, and this is a game after all), and why smaller, well designed rockets can fly much further and faster.
For any launcher, a general rule of thumb is that each stage should have ~3x as much fuel as the stage above it. To achieve this, it is common for structural adapters to be used to increase the diameter of the rocket from top to bottom. There are several different sizes to choose from, and most parts have at least one option in each radial size. For example, fuel tanks come in both different diameters and different heights, and the amount of fuel they hold varies linearly with volume. There are also (usually) multiple engines for each diameter, but rather than varying in height, they vary in thrust (the force an engine puts out), Isp (the fuel efficiency of an engine), and gimbal range (stability provided by engine). In KSP, the fuel consumption rate varies as a function of thrust and [Isp]] (w:thrust is held constant and Isp varies with atmospheric density.
The traditional composition of each stage of a launcher (except the first) is a decoupler on top, a structural adapter to increase thediameter (this is optional), a liquid fuel tank (liquid fuel and oxidizer in one tank is best for rockets), and a liquid fuel rocket engine on the bottom. For higher stages, a lower thrust engine with higher Isp is typically used. For lower stages, a higher thrust, lower Isp engine is used. The goal is to maintain a thrust-to-weight ratio of greater than one for each stage and its payload. These stages will rarely have parts radially attached to them. Some exceptions to this are reaction wheels (if more stability control is required, control surfaces (same objective, but only work in atmosphere), and small drop tanks (for asparagus staging).
The first (bottom) stage of a launcher is almost always the largest, both in height and diameter. This stage will have multiple engines, and if you were waiting for solid rocket boosters, radially mount these here (usually on top of radial decouplers). You can also use the stock liquid booster or build your own using a liquid fuel tank with a liquid fuel rocket engine on the bottom. It should be considered that solid rocket boosters cannot be throttled or turned off, while liquid fuel rocket engines can be. This stage will typically have wings, winglets, or control surfaces for stability while in atmosphere.
The bar of icons on the right side of the screen during construction (left during flight) is the staging list. This list is the order that parts will be activated during flight, and is a very important part of any successful launch. The list is executed from the bottom up (representing the way a rocket works), with the highest number stages being activated first. Whenever you place a part, the game will place that part's action icon into the staging list where it believes it should be. This is based on the dependency list of parts for the craft however, and is therefore not necessarily the order you want your parts to be activated in. Luckily, the order can be changed manually, both in VAB/SPH and during flight. To do this, you break the "you never have to hold down a mouse button to interact with stuff" rule. To select an action icon, simply click once on it. To move a selected action icon, you click on it, hold, drag, and release it where you want it. You can select multiple icons at once by holding control and clicking on each of them. Staging into an action icon (via spacebar), triggers a different response for each part type (not all parts have action icons in staging, fuel tanks for example). For engines, it turns the engine on at the current throttle setting (note, SRB's cannot be throttled, and are just 'on'). For decouplers and separators, they separate the connected components from the craft (these cannot be reconnected). For parachutes, they are activated (will deploy when minimum pressure requirement is reached). For launch clamps, they release the craft. No other part types have action icons. Every action icon in the same "stage number" on the list will be executed simultaneously, except in cases of extreme lag. Additionally, entire "stage number" groups can be moved together by clicking on their number and dragging. You can also add and delete stage number groups by clicking the + and - buttons next to them.
For a reasonable staging setup for a rocket, the bottom stage engines, boosters, and launch clamps should be in a single stage on the bottom of the list (highest number). From there, you should detach radial boosters as they burn out using radial decouplers (make sure radial detachments are symmetric to avoid throwing off the rocket's center of mass, and finally dropping the entire stage via adecoupler or separator. Once dropped, you should activate the engine at the bottom of the next stage, and repeat as above!
Commonly known as planes, these are most often constructed in the SPH. The SPH is advantageous for the construction of aircraft and spaceplanes due to its use of bi-lateral symmetry (since they don't need to be vertically symmetrical, only laterally), and its easy access to the runway. The controls function exactly the same here in the SPH as in the VAB, as explained above, the only difference is that the vertical "stack" is now horizontal by default. It should be noted that saved vehicles are only available in the structure where they were built, though subassemblies do transfer back and forth. The part most commonly used on these types of vehicles is the Small Gear Bay.
Pending re-write for post-release aerodynamic model.
An aircraft is any vehicle designed to use lift as its primary method of staying airborne. This requires the use of parts that aerodynamic|produce lift, such as wings and winglets. Generally, the primary method of controlling an aircraft is by using control surfaces, though reaction wheels or RCS are used in rare circumstances. To build a longitudinally stable aircraft in KSP, the center of mass should be in front of the center of lift. The further apart they are however, the more pitch force is required to maintain level flight. This is usually generated by control surfaces in the form of a horizontal tail or canard setup. To maintain yaw stability, a vertical stabilizer should be placed near the tail of the vehicle, and will typically consist of a wing or winglet and at least one control surface. A vertical stabilizer, as well as the wings themselves contribute to roll stability.
Thrust in an aircraft is typically produced by jet engines. They require liquid fuel and intake air which are provided by liquid fuel tanks and air intakes (they do not require oxidizer). With the exception of the Rapier, jet engines only operate in atmospheres containing oxygen (Kerbin and Laythe).
A spaceplane is a vehicle that is intended to fly in space which takes off and lands horizontally like a plane. This is distinct from a shuttle, as those use a vertical rocket to reach space. Similarly to aircraft, spaceplanes utilize lift to fly while in the atmosphere; however, spaceplanes are meant to also operate in space, so they sometimes require rocket-like features.
In addition to the stability concerns for aircraft mentioned above, the center of thrust is very significant. If the thrust vector (shown in center of thrust display) does not line up through the center of mass, then large amounts of SAS input may be required to keep the vessel stable while in space. Because of this, spaceplanes will have reaction wheels and/or RCS in addition to control surfaces.
For propulsion, spaceplanes will typically have both jet engines (for in-atmosphere flight) and liquide fuel rocket engines (for in-space maneuvers). Construction techniques for spaceplanes will be covered in Advanced Vehicle Construction below.
For controls, see Rocket Staging above.
The only difference between staging planes and rockets is that planes rarely use decouplers. Because of this, the most common setup is to have all engines activate at launch and then toggled on and off when needed using custom action groups that will be described below.
Aside from rockets, aircraft, spaceplanes, etc, it is also possible to build ground and sea vehicles in KSP. By far the most common ground vehicle is the rover, for which there are a variety of wheels available. Wheels can be popped from impacts and excessive speed, and can be repaired via EVA, covered later. Unmanned, as well as manned rovers can be built, and an external seat exists for just that purpose. Additionally with the updated water physics, boats, seaplanes, and submarines are now a possibility.
Setting Action Groups
Action groups allow you to bind part actions to the number key row (1-0), as well as to the default groups such as landing gear, lights, brakes, SAS, RCS, and abort. Using these, you can simply press a button and have a part (or a group of parts) do something. This is very useful for several reasons: 1) there are many actions available that are not available through staging, 2) they can be used to toggle, rather than simply activate, and 3) they can be used repeatedly without having to reset them.
Action groups can only be set during construction in the VAB/SPH, and cannot be modified during flight. To set action groups, select the blue icon that looks like gears from the top bar of the VAB/SPH. Next, select the group/key you want modify (1-0 and abort are empty by default, while some parts automatically bind to gear, lights, brakes, SAS, and RCS) by clicking on its name in the left hand bar. Now click on the part you want to add to that group — it will bring up a list of available actions for that part. You can add one or several actions to the group by clicking them in the far right column, and remove them by clicking them in the middle column (they will move back and forth). To add actions from another part, simply click on it and then add its actions. A full list will compile in the center column showing all the actions in the group (sorted by part), and actions can be removed at any time prior to launch. After setting your action groups, be sure to save the vessel, otherwise they may be lost if you attempt to launch.
When you select a part to add actions from, it automatically selects all of its symmetric parts and adds the same selected actions for them to the action group. Also, some actions are contradictory (ie, activate and shut down) and the game will perform both of them — however it is difficult to predict which is executed second, as this is typically the action you will observe. Finally, if you make modifications to your vessel after leaving this tab, your selections may behave erratically — therefore setting action groups should be the second to last thing you do before launch (after construction/staging and before crew placement).
Action Group Usage
- Replacement for staging in rockets — some players consider action groups to be more reliable than staging, and therefore use them to activate engines and separate stages instead of spacebar.
- Performing a large number of actions (not available in staging) simultaneously — this is the most common usage in rockets and spacecraft in general, as using the right click menus to open a bunch of solar panels is very time consuming.
- Performing an action (not in staging) quickly and/or repeatably — this is used most often in spaceplanes to open/close air intakes and switch from air breathing jet engines over to rocket engines. It is also sometimes used to activate science parts at a particular moment in time, and to easily find unused science parts.
The crew placement options are accessed in the VAB/SPH, much like the action group controls, by selecting the blue button representing a Kerbal near the top center of the screen. Once on that tab, you can drag Kerbals to and from the seats available in your craft. Making any modifications to your vessel after leaving this tab will reset the crew changes you made, and the save button will not save your crew selections. Because of this, crew selection should always be the very last thing you do before launch (after construction, staging, and action groups). After launch, the only way to move Kerbals to other modules is via EVA, and specific seats cannot be selected. It should be noted that you cannot place crew into the EAS-1 External Command Seat from the VAB/SPH.
What Can I Do?
Kerbal Space Program is a sandbox style game, and with that focus comes the ability to do anything you want! There are 3 different game modes, a few built-in scenarios, and a user-written campaign. Additionally, there are many user-defined challenges on community websites.
The purpose of career mode is not just to explore or have fun, but to handle all the aspects of managing a space program. Update 0.22 added science to the game, and update 0.24 added funds, reputation, and contracts. Squad has plans to continue to expand career mode.
In addition to simply flying vessels, kerbals can leave their craft and go on an extra-vehicular activity (EVA). While on EVA they can walk/run, use a jetpack, take surface samples, and plant flags on other worlds. Most players enjoy these activities, and many of these contribute to gathering science points.
When KSP was first released, Sandbox mode was the only way you could play the game. It allows you to use all the parts with no limitations, letting you build whatever kind of rocket or plane or rover or whatever your heart desires. There is no wrong way to play the game, merely less efficient ones. Sandbox mode is all about having fun — by doing whatever you find to be fun!
Sandbox mode's biggest perk (no guidance) can also be a hindrance to some players who cannot decide what they want to do, and end up bored. For these players, either career or the campaigns are a good starting point, as they will give more specific guidance.
There is a series of user written campaigns that are designed to provide guidance and challenges to players. They focus on historical and probable-future events, such as moon landings and mars exploration. They provide a reasonable learning curve of difficulties, following a step-by-step progression to "bootstrap" your way across the Kerbol System.
Advanced Vehicle Construction
This section is WIP.
How To Fly Your Rocket
The first thing you should know when controlling a vehicle is how to stop controlling said vehicle. This is done using the escape menu, aptly named because it is accessed by pressing the Escape Key on your keyboard (shown as Esc). This will pause the game, and provide access to a menu that includes some or all of the following:
- Return to Game: returns you to your active vessel.
- Return to Space Center: leaves the active vessel and returns to the KSC scene.
- Return to Tracking Station: leaves the active vessel and returns to the Tracking Station interface. This option is not always available (reasons unknown).
- Revert to Launch: reverts your entire game back to when you placed the vessel on the Launchpad or Runway. This option is unavailable if you have left this vessel since launch.
- Revert to Construction: reverts your entire game back to just before you pressed the launch button in the VAB or SPH. This option is unavailable if you have left this vessel since launch.
- Settings: accesses the game's settings menu. Not all options are available here that are available in the main menu's settings menu. The game remains paused while the settings menu is open.
When the escape menu is closed, the game is unpaused.
When pressing the escape button at the KSC scene a similar menu appears, with the addition of the "Save Game" and "Quit Game" buttons. The "Save Game" button here actually creates a nameable quicksave (explained below), and the game's persistence file (the actual savegame) is autosaved periodically and automatically upon quitting the game.
A useful feature that is not displayed in the user interface is the ability to quicksave, and its counterpart quickload. These features allow you to save the entire game at any point (even while flying, and with 0.24, even while throttled up) by pressing F5, and to load the most recent quicksave by holding F9. WARNING: Using quickload will revert your ENTIRE GAME and CANNOT BE UNDONE. With update 0.23.5 came the ability to name quicksaves by pressing Mod+F5, and to load a specific quicksave from a list by holding Mod+F9. In 0.24, the ability to create a named quicksave from the KSC scene escape menu (seen when trying to exit the game) was added in order to encourage players to quicksave before closing the game. This was done to minimize the irreparable losses incurred by players who use quickload on the assumption that they had quicksaved recently (when they had not) and accidentally reverting their game several (real life) days.
What your rocket is trying to tell you... WIP
Time warp allows you to fast forward game time. This is very useful, seeing as any space mission played fully in real time could take days, and that most missions consist of a few planned maneuvers with a lot of time in-between with nothing to do. This control is always available in the top left of your HUD during flight, with a maximum time warp factor of 100,000x. Aside from clicking on the arrows, you can also apply time warp using the , and . keys (representing the < and >, but simplified so that pressing shift isn't required). Classic "on-rails" time warp has a minimum altitude for each body and cannot be used while the vessel is under acceleration. Alternatively, "physics warp" can be used any time by pressing Mod+., but has a maximum time warp of 4x and can cause physics errors that commonly lead to the destruction of high part number craft.
A stage is defined as a subset of ship that are all activated simultaneously. More...
Going sideways. WIP ROT vs LIN controls
Were lost, aren't we... WIP link to maneuver nodes
The things you want to see. WIP
Into the frying pan. WIP
There may be snacks inside... WIP
Flat tires and broken suspensions. WIP
The Navball is usually used as a compass in launching rockets, because it shows the heading of your rocket in respect to either Surface, Orbit or Target More...
How to get to SPACE. WIP
Landing without lithobraking. WIP
Surviving the fire. WIP
All things that are not space. WIP
Flying things in space. WIP
How to make use maneuver nodes to plan burns. WIP
Best ways to change your orbit. WIP
Advanced Orbital Maneuvers
Other interesting things to move your ship. WIP
Much impress, wow. WIP
We need to slow down first! WIP
Pre-Release Aerodynamics (outdated)
While planes can be built using similar principles to rockets (see F-4 Phantom), the biggest advantage they offer is their ability to use lifting surfaces effectively. The way stock aerodynamics work in KSP produces a conundrum that causes the classical laws of real aerodynamics to be thrown out the window. This is present in rockets, but is much more prominent in planes. The problem is that KSP applies drag as a function of the drag coefficient (0.2 for most parts) and wet mass (including fuel) of each part. This drag is then applied from that part's center of mass, causing the total drag to be applied from near the vessel's CoM. For maximum stability in a real airplane, you want the CoM and thrust in front, followed by the center of lift, with the center of drag behind that (note that this theoretical plane would be too stable to maneuver). Because of the way drag is applied here, it does not apply a stabilizing force in aircraft. However, this effect can be countered in KSP by keeping the center of lift well behind the center of mass using wing parts (the only parts that generate lift and thus effect the center of lift). The closer the center of lift is to the center of mass, the more SAS force is needed to keep the craft stable. If the center of lift is ever forward of the center of mass, then even SAS will not be able to keep the craft out of an uncontrollable spin (or even stuck flying backwards). Additionally, there is no "interference" between parts, so therefore every non-physicless part contributes to drag regardless of its location (ie, inside a fairing). See Advanced Vehicle Design (below) for other stability, lift, and drag considerations.
With the limitations of this old stock drag model in mind, the community has developed several alternative aerodynamic models, which can be found here. It should be noted that some of these addons alter gameplay significantly.
Get to know the flight HUD (old)
At this stage, you should be sat on the launch pad, desperate to send some poor Kerbal on a wild mission. Before you go and crash in blaze of fiery glory, I suggest you take a moment to see what is going on. The main feature you will see in the middle bottom of your screen is the Navball, this will be the main way you know what is going on with your ship.
Down the left hand side of the screen you have the staging for your ship, which if done in a sensible way you can more or less ignore, but it is handy to have. And in the lower left hand corner are a few fancy dials, they show you the pitch, yaw, roll and stage for you ship, and again for the most part you can ignore this.
At the top is a fancy gubin that shows 'height' related details. The altitude gauge is vital when it comes time to land; the only thing you need to keep in mind is that it is the height above sea level that your command pod is, so if you have a ship that is 10m tall and it is currently reading 11m you better hope you are ready for a nice soft touchdown. The circular dial is for your vertical velocity; you should keep in mind that this has 'zero' vertical velocity in the 9 o'clock position and that it is not linear. The fact that it is not linear means it can show you rather precisely as you transition from 3 m/s to -1 m/s but when you reach higher velocities it becomes rather vague, showing your speed in ever large increments. The last detail to look at on this panel is the atmosphere. This shows you a rough guide of how thick the air is; the thicker the air, the faster you slow down, and the less you can time warp.
The last detail to mention about the HUD is that in the lower right hand corner, you have a live feed of your kerbal crew, usually either screaming in delight or terror. As far as I can tell, their reaction has no relation to the peril they may really be in, though they always seem to welcome a gentle approach to the surface.
Basic Orbit Control (old)
First, let's define an Orbit; simply put, it's falling around another body in space, ideally never colliding with it. The idea of 'always falling' is odd I will grant you, but either accept it, or better yet, go read up on it.
As you leave the launch pad, and start to turn to side, your orbit will start to form. The point at which you would crash back to Kerbin (or what ever body you are taking off from) if you cut the engines will slowly start to move further and further around, until eventually you will no longer fall all the way back to the surface. You have now successfully managed to get into orbit! Though chances are, you will have a very erratic orbit; basically egg shaped. There are two keys points on your orbit, the Periapsis and Apoapsis; the Periapsis is the closest to the body you are orbiting, the Apoapsis the furthest. When you are at these two key points, your vertical velocity is zero. Note that you are still travelling very fast, just your altitude is not changing (for the very brief moment at least). The difference between the Apsides (that being the plural of Apsis, that being what these two points are called collectively) determines how eccentric your orbit is considered, though for basic game play, this is not really a concern.
When manipulating your orbit, there are two key things you want to do, change its height and change the 'plane' at which it sits. Changing the height is very easy to do, aim to adjust the height of one Apsis whilst you are sat at the other Apsis. If you try to change the height at the point you are, you will have to 'burn' a huge amount of fuel to stop your orbit, let your self fall back or burn to push out, then burn to get back in orbit. All told, a whole lot of burning fuel, it is far more efficient to just burn at the opposite Apsis. If you want to raise an Apsis, point into the direction of travel and accelerate, to lower the opposite Apsis, point you ship backwards and fire the rocket so that slows you down. If you use the Map view you should see the Apsis change, don't forget that you can hit 'X' (by default) to turn off your engines. If you are very low on fuel, remember that the most efficient time to burn is that split second when you have zero vertical speed, so you are going to want to do a lot a very small burns.
The other important manipulation you will want to want to do, is rotating the plane at which your orbit sits. This basically relies on Gyroscopes, which are frankly a mess to try to explain how they work, so it easy to simply say, "If you want to push a point in your orbit in a certain direction, do it 90 degrees before the point you want to move". Feel free to go read up on Gyroscopes and how they work and all that jazz, but trust me, "90 degrees" is a lot easier to remember. It will also be easier for you to manipulate the plane the smaller and more circular your orbit is, so getting the nice orbit is worth practising, and will come into play when moving to the next section.
The final thing to mention about orbits, is transition orbits, moving from one body to another. You should try to get your orbital plane in-line with your target body, this way you can allow your self a bit more freedom with exactly where you meet the target body. You should also try to get your orbit as circular as possible, this will make it easier when you are ready to burn to get out to your target. The last detail is hard to provide a generic guide for, as it basically depends on what you are currently orbiting and what you want to move to. As a starting guide, I will say that go from orbiting Kerbin to orbiting Mun you want to be orbiting towards the east, at around 100 km altitude, as you see Mun rise on the horizon from behind Kerbin, start your burn until your orbit starts to interact with Mun. You know your orbit is interacting as the 'flight computer' will show an arc for part of the orbit that is around Mun. Once you are set up, time warp until you are just about to enter Mun orbit and prepare to burn to get your orbit to be stable.
IVA and EVA (old)
IVAs (Intra-Vehicular Activities) are where you get to see a first person view of the inside of your ship. You can still make use of all your normal ship controls, but now you get the delight of seeing the dials spin and the throttle move up and down. Frankly, there are not enough blinky lights to keep me happy, but still, it looks pleasing enough. I imagine that in a future version, if you are docked, you might be able to float around inside your ship.
EVAs (Extra-Vehicular Activities) are where you let one of your buddy astronauts float around in space. This can be a potentially serious risk to your guys, as they (currently) have no tether to prevent the drifting off into deep space. In theory, when you little guy first gets out of the ship, he will hold onto the ladder of the capsule, but there can be cases where they decide to just float away from your craft. As long as you are able to keep control your guy, you can use his jet pack to float around the ship. If you dock two ships together, you can transfer the crew through the docking ports. First, left click on the door of the first craft, then click on "Transfer" next to the kerbal you want to transfer, and finally left click on the craft you want to move the kerbal to. You should also be able to send a guy from one ship to another via an EVA, just as long as he has a free seat in the ship he wants to board.
Finishing words (old)
Hopefully (and I know not yet based on the current state of this) you will have a good understand of the basic mechanics of the game. From here I suggest you play around for a bit, maybe set your self a few missions. It might also be wise to read up on how orbital mechanics works, as a better understanding of the maths and physics will really help out.