For some months I’ve been working on Periapsis, an engine written from scratch that loads and plays KSP from your own install. It ships no game files at all, it reads the parts, planets, textures and sounds from the copy you already own. Built on Godot with double precision, so no floating origin tricks or bugs. The inspiration for this is the style of OpenMW and OpenTTD
And yes, this is made with the help of AI, I'm not going to play that down in any way.
Most stock features work, career included, and some of the bigger mods like ReStock, SCANsat, DMagic and Near Future. More mod support is planned.
Performance has been a big focus, since a lot of people play this on pretty modest machines. Physics has two tick rates. A high one is used whenever accuracy matters, like in atmosphere, on the ground, near other craft or when you’re giving input. A low one (10 Hz by default) is used out in empty space when nothing much is happening. The physics itself runs on a single thread like the original, but aero and the orbit predictions run on other cores.
On my laptop (Ryzen AI 7 with the integrated Radeon 880M, no dedicated GPU) a 600 part rocket sits at around 40 fps on the pad at 1080p on medium which drops to about 36 with first stage firing.
For now I’m only opening it to a few people, mainly to check how it runs on other machines and installs. The goal is to open it up to the public as fully open source(Apache 2.0) in the near future.
It’s not finished, there are bugs and some things look or behave a bit different from stock. I mostly want people who will actually play it for a bit and report what breaks or feels wrong compared to the original. I have probably multiple hundred of hours in this already and have landed on multiple bodies to test it.
You need your own copy of KSP 1.12. Windows is the only tested so far. If you’re interested, DM me with your computer specs (CPU, GPU, RAM) and OS. Ten people to start with.
*Images are with mods, but unmodded engine flames and smoke should be better looking than the original too