About the warning: this is absolutely true. I initially wanted to make the timer flash red when the time was low, but this didn't manage to make the cut. It's an important piece of polish, I agree with you.
About the body: you're not the first person to report on this and in hindsight I made a mistake. The color of the body is a more desaturated version of the sprite when "alive", so it tends to get lost. I also noticed this through playtesting, but didn't realize how big of a deal it was because I knew where to look for the body in the first place.
The ESC to restart issue has been reported. I think it happens on windows too, and I'm using a mac myself and I recall it worked fine when I playtested, so it's probably a subtler kind of bug. I'll look into it!
The "winning" screen turning into a "losing" screen after alt tabbing is very unusual and you are the first to report it. It's very odd and I'll look into it.
Noted! There are some other spots where it's a little hard to examine what you want, so I'll have to improve the system.
The lack of music is an important point. It's just that I am kinda crappy when it comes to sounds and music so I tell myself I'll add them later, which usually results me in being too tired to eventually care about them. I had to push myself to include the few sounds I did :p I realize this is not ideal so next time I'll work on sounds while I program just like I work on art and animation at the same time.
The randomly generated mansion is a great idea I considered, but just like more suspects and more weapons, it's something that had to fall on the cutting floor for time constraints.
Thank you for your long post and valuable feedback!