I would prefer instructions in game rather than in game description.  There's also a bug where you get stuck on some objects when moving (from experience with GMS it should be a pretty easy fix to the collision logic).

I'd also say it's still a stealth game with stealth.  You still have walls to hide behind and enemy FOVs to avoid.

Great game, and I loved the disguise machinic! It is rather short since this is only the first version, but I will bookmark this so that I can find it if, or when you release further stages!

The controls are a bit wonky at times, but the general idea is pretty good.