Early Versions

The first released version of Kerbal Space Program is version 0.7.3 , released on June 24, 2011. However, this is not the first version of KSP.

The development of the game actually started on January 17, 2011, when the programming of the game began. The first versions created were intended to prove that the project was feasible and contained only the bare minimum of the functions of the game. These versions have never been made public, and there are only a few images from Felipe's blog Falanghe, said HarvesteR, the game's development team leader.

HarvesteR revealed these images in 2012, on the occasion of the first anniversary of KSP, and gave some information on it. It only talks versions 0.0 to 0.4, and does not address versions between 0.4 and 0.7.3.

Version 0.0

The very first version of KSP was created to show that the HarvesteR concept had potential: it was not even a game, there were no controls or camera movements, the terrain was just A green plane, the rocket and the firing point of the gray cubes, and the sky one of the default backgrounds of the Unity engine. This prototype just showed a rocket take off automatically, without being able to direct it.

The only existing image of version 0.0.

Version 0.1

It is in this version that the rocket editor appeared. The VAB did not yet exist, the rockets were built directly on the firing range: the editor also included the first swiveling camera of the game. Interestingly, the game originally had to be in 2.5D: the set was In 3D, but the rocket could only be directed on the X and Y axes, not the Z axis. A simple terrain had also been created, but it was flat and could be pulled out, causing the rocket to fall into the Absolute vacuum.

A rocket made up of all available parts.
A field collision test.
The first editor of the game. There were then only 5 different pieces, no backup or management of the floors.
The terrain of version 0.1: note that there was then nothing beyond a certain distance.

Version 0.2

Kerbin appeared in this version, at least in the form of a sphere of 20 km in diameter, in order to develop a realistic gravity. It is also in this version that appeared the ancestor of the orbital map, a simple black square indicating the trajectory of the rocket.

The rocket editor is slightly improved, the order of the floors is now displayed on the right.
The firing point. The moon in the background is just a scenery and is not explorable, unlike the Mun.
A rocket in orbit. Note that there is not yet any spatial decoration, just a blue background.

Version 0.3

This version focused on the interface: the windows aspect was improved, a panel in the editor gave some information and many indicators appeared on the right of the screen. However, bugs and compatibility issues have forced developers to abandon this presentation. A "manual" of instructions was also created, and had to appear before starting to play, which will later give rise to the tutorials.

The information panel, supposed to give tips to the players.
The firing range and the new interface. Note that many instruments are not yet programmed, such as portraits of the Kerbonauts.
The "instructions" of the game, ancestors of the tutorials.
A rocket in flight. Note that the terrain is not at the point and disappears to the right.

Version 0.4

This version is the last one we have information on. It focuses on the field. In this version, the Kerbin terrain was really designed: HarvesteR first tried to generate it randomly, then using sound waves from the LibNoise library, but this process was not effective for a flat world and not spherical. HarvesteR then developed a system for generating terrain within a certain radius and whose details would fade with distance. This procedure was difficult to codify, but ultimately gave a satisfactory result.

An asteroid generator designed by HarvesteR, which could have been modified to generate planets.
An attempt to generate the land.
Another improved attempt.
The system of generation of the ground by "discs" of HarvesteR.
A rocket in flight with the new terrain more detailed.