| Parts unlocked with
|Parts paid with Funds||Yes|
|Reputation to Kerbals||Yes|
The Career game mode is one of the three in Kerbal Space Program. Compared to other modes, Career focuses on managing resources like funds, science, and reputation. The heart of Career mode is the contract system, where players complete certain tasks to gain these three resources.
In Career mode, building and launching a rocket costs funds. Funds can be obtained through contracts, which are given by agencies to earn money to fund future missions of the space program. The Mission Control building is used to manage available, active, and finished contracts. Accepting and completing a contract will earn the player funds, and raise their reputation. 
Like Science mode, the player can use the Research and Development facility to "research" new parts. The player can use only parts which are already unlocked, so every game starts with the Start node unlocked.
An important feature of this game mode is the kerbonauts' specialization and experience system, based on XPs gained by reaching achievements. These progresses can be observed most comfortably in the Astronaut Complex.
The buildings of the KSC starts fairly undeveloped, and have to be upgraded for funds () to be useful for further development.
The easiest first mission is simply “launching” the Command Pod Mk1. This is similar to the first Mercury and Vostok missions.
The first rockets could go anywhere in the vicinity of Kerbin, especially with techniques like explosive decoupling. However, most early rockets will barely, if even, exit the atmosphere. Even so, landing in a new biome means a fresh opportunity for science activities.
It's easy to unlock the first four nodes of the tech tree by performing science activities around the Kerbal Space Center, even with only Start node parts. The KSC contains many special surface-only biomes. Regular biomes outside these special biome locations include opportunities for science while the vessel is flying or in space. At first only Crew Reports can be done without upgrading any building. Crew Reports only yield science points the first time performed in a situation and biome. So, visiting the same biome multiple times without having new science modules on board isn't very productive.
To accelerate the amount of science returned, it's wise to unlock nodes offering new science modules. With these it is possible to gain even more science to compensate for the fact that technology tree nodes become increasingly expensive. Upgrading the Astronaut Complex and Research and Development facility allow taking EVA Reports and Surface Samples.
Later nodes will be difficult to unlock without visiting other celestial bodies. Kerbin's moons Mun and Minmus are primary targets for the middle game as they can be reached quickly and easily. Both also feature biomes, greatly increasing the amount of science that can be collected.
It will be important to unlock various batteries and solar power generators for transmitting data. Missions will generally be larger and demand greater mastery of the maneuver node system in Map view.
With good strategy and diligent "mining" to exhaust biome+situation combinations, it's possible to finish the tech tree with just Kerbin and its moons; but it's often faster and more exciting to figure out how to intercept with other planets. Eve and Duna are certainly reachable with conventional rockets. For manned exploration of distant planets, and the high multipliers for doing any Science on them, acquiring the LV-N Atomic Rocket Motor will be very helpful.
- “First Contract Playthrough” by Miguel (Maxmaps) uploaded on the official Kerbal Space Program channel released on the 11 July.