I REALLY dig this. The gameplay is a ton of fun and addictive. The autoaim is nice and convenient. The dynamic music is real cool. I love how it evolves as you go down each floor - makes me anticipate what the next floors will sound like. The falling sequences are fun and look very cool. The footprints are a nice feature, very useful for making sure you've visited all rooms! No real complaints, though I instinctively pressed ESC expecting to pause the game but instead triggered a game over :(
Overall, very fun game!