I just tried the game (Debian testing, x86_64). It launches, but the mouse doesn't work at all in the game which kind of defeats the purpose. Any suggestions what's wrong?
When I manually set "Screenmanager Is Fullscreen mode" to 0 in $HOME/.config/unity3d/14HoursProductions/DeadHorizon/prefs, the mouse starts working (and the game runs in windowed mode). It's some kind of Unity issue I suppose.
At least I can still make it fullscreen with F11 (KDE), so it's kind of a workaround.
UPDATE: Just finished the game. Nice work!