Thank you for your highly constructive feedback!
About the enemies: Yeah, the original idea was to leave enemies totally invisible, but I thought it was a bit annoying to play then. In the other hand, leaving the eyes visible perhaps made the game a bit too easy. Decisions, decisions...
About the game window: Resolution of the game is whopping 192x108 pixels, and the game is supposed to be played fullscreen (in the matter of fact, it should start as fullscreen by default). I know that some people prefer to play windowed, and for some reason I just forgot that… Sorry about that!