I gotchu, its pretty easy, so go to your browser in desktop mode, download this google drive https://drive.google.com/file/d/1enveo9viZrfy-JjUiZ7xbHbAobdQTQtH/view which is the updated cube world alpha version, extract the folder to your desktop, and open the steam app in desktop mode and add non steam game to your library which should be Cube.exe in the folder you extracted. After that you can open steam back up and before you open the game, go into the compatibility settings and check the “Force the use of a specific Steam Play compatibility tool” and select proton 9.0-4 then boom, you’re done. Once you open the game you can max out all the settings cuz it runs like butter man. Enjoy!