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KSP's spiritual successor Kitten Space Agency just released a free public pre-alpha
(www.youtube.com)
https://ahwoo.com/store/KPbAA1Au/kitten-space-agency
You can zoom out from a craft to the solar sytem and beyond (interstellar is on the roadmap), and it's completely smooth and seamless 
Also, I love the cat theme, but I'm very divided if I can ever stomach launching a mission with a crew based on my IRL cats 
Runs perfectly on linux
I successfully crashed the starter ship into mexico city at several km/s and became a spinning jetwheel of death and distruction, the game is perfect, no updates needed
How did you run it? Proton?
Yeah, proton. First used proton through steam to run the installer. Then I used proton through steam to run the game's exe. then it yelled at me for not having .net so I used protontricks to take care of that. and then it just worked