Cool concept! The initial presentation was great, and the art / audio is really well done.
It was very unclear how to spot the spy. The "hint" of "he is slightly faster" was somewhat helpful but overall just comparing the speeds between various guests wasn't very fun. When the dossier said that he was "stealing objects" I was expecting to be able to spot him doing this, but it didn't seem like the level contained any objects that he would be doing, everyone just wandered randomly. It was also unclear that I needed to click on him multiple times... he just turned green at first.
The "dance" part was a fun little DDR thing, and was a really cute way to beat the game. The music does get desynced from the arrows about halfway through the song though.
Overall good job!