This puzzle type is from the latest World Puzzle GP (gp.worldpuzzle.org) round last weekend, and I made this one after misreading "intruder" as "impostor". Colors are only there for aesthetic purposes and do not affect the puzzle solution ^^

Update: I have now learned of the german belief that it is bad luck if people wish you a happy early birthday. I may have invited a ton of bad luck onto myself.

should be set up now, search "pencil puzzles" in feeds and it'll show up~