I really like this idea! It's great that you went beyond just "play as a ghost" and added a really interesting turn-based, strategy element to it. I think you could get a lot of mileage out of this idea if you changed it from the Pac-Man theme into your own unique game. It might also be really cool to impose similar movement rules on each ghost type, so that depending on which ghosts you have in a certain level, your tactics might be wildly different than the previous level. For example, maybe some can only turn certain directions, some move faster/slower, some can dash quickly for a few seconds and then need to rest, or some can respawn while others die permanently if eaten.