Huh. If I unfocus the window to do anything else for a second, and then come back, all of the controls stop working.
And it performs awful on my 4-year-old laptop. The further I go, the more often and longer the pauses in responsiveness are. I assume it's having to garbage collect more often or something. My computer heats up like I'm running a game from like 2018, and I'm capping 4 CPU cores when it pauses like that.
Took some screenshots to make sure scaling was right (it was) and found out Unity is being stinky and giving you four visually distinct colors, but with multiple different versions of each color. It reduces to about 30-ish colors in a palette, even though it visually looks like four. Even from one color variant to the next, it looks the same, but they have slightly different hex values. It seems these slight color variations are mostly on the edges of objects and such.
(TBH I'm noticing a pattern where Unity keeps tripping up people trying to adhere to the color and screen size requirements. This is relatively minor, since it still looks like 4 colors, but something to tweak if you move forward with developing this.)
The atmosphere is spooky and unsettling, tho. Really nails that feel that something is off (aside from the corpses and rambling of who I can only assume was their killer). The minimal background music adds to the mood. The visuals look good, too. The slow drip of information as you progress though the same hallway again and again is perfect for the mood this sets.
It seems dubious this would run at any usable framerate on a GameBoy, though, even with better optimized code.