You are correct, you would have to launch it from a Bash script because of how it needs to hook BepInEx on Linux (something I'm really hoping I can change)
I'll have to look into this and see if there's something I can glean from the SteamOS beta. I think I do know what causes the bug; it most likely has to do with the pixel-perfect renderer the game uses. The game strictly relies on not just its native aspect ratio (16:9 with the borders), but also the 320x240 pixel-perfect camera the game is rendered with. Whenever the window's scale is changed, if it becomes too small for the current resolution (or if it becomes a lot bigger), it will try to scale everything down or up by a power of 2. I think it believes the window can't fit the game when BepInEx is installed (however it determines that), so it increments the full resolution down by the next power of 2, putting it at half resolution.
The key here definitely has something to do with the window size, so I'll have to see if maybe there are launch options or something if Steam's resizing options don't do the trick.
Regardless, thank you for letting me know about these changes to SteamOS, and sorry it isn't working! I'm hoping I can figure this out and update the guide.
