Just tried KARLSON on linux (ubuntu 18.04 kernel 5.4.0-47-generic)
So far the game seems to be running smooth but the brightness is very low. I upped my brightness all the way to maximum and it was still hard to see what was going on on-screen. In your videos it looks way brighter so I suspect it might be a linux specific unity thing.
Thought I would mention it.

Nice job though (even though I suck at this game).