The theme really reminds me of Spy Party. I like how you have to find some sort of intel to identify the spy.
Some things I'm having difficulty is seeing what color is which and who exactly is the guardian. Maybe the guardian should have a slightly different design from the rest of the guests? Another thing is that I didn't quite feel the time pressure of a spy trying to hunt me down. Also I think it'd be pretty neat if the intel required some kind of task in order to accomplish rather than you just walking over to a spot and picking it up.
Pretty unfortunate you have the NPC kill bug, but great baseline for a game!