I can play smoothl until a random person apperas at the bottom and crashes my game
Xenosphere is a more experimental game than it may first seem, as the disclaimer on top of the page indicate. It shouldn't crash the game though if you're running it on Windows 10 or 11, that may be some system incompatibility problem?
If I can see your player.log in %USERPROFILE%\AppData\LocalLow\Nifflas' Games\Xenosphere I could maybe pinpoint the cause of the crash?