First of all: man, what a beautiful job we have here! Seriously, great demo! It will be a great game, with a nostalgic aura! Very good!
Second: I'm a Linux guy, but actually I have a PC in dual boot with Windows. I tested the game in both OSs, and I noticed some diffrences in the run. I'm just giving you a feedback.
- In the Windows version, the game runs in a 4:3 aspect ratio (and I think it's intentional, for nostalgic reasons). The Linux version runs in 4:3 stretched. I don't know if it's a bug or it's a Linux configuration thing.
- The Linux version won't detected my controller. I've tried a generic one, and a 8BitDo Zero also. None of them worked.
Congratulations for the game! Nice work!