The game was fun and had a nice ambiance. Nice interpretation of the theme. Had a very Ghostbusters feel.
The slingshot wasn't always killing bats even when the shot detonated on them. Though they were always stuck and not moving so not game-breaking. What was game breaking is I couldn't fight the Alien Lord. I activated it, the barrier didn't drop. I'd already captured the vampire lord, and the game wouldn't let me fight the mummy lord.
Overall it has a lot of promise.