The central idea is interesting, and works reasonably well.
Here are a few things you could do to kick this game up a notch:
- The enemies could move a bit on their own--otherwise, it is too easy to just avoid them as you search for the exit.
- The dungeon could have contents to explore and negotiate, such as walls and furniture. The player might have to search for a path towards the exit.
- You could add some collectibles, maybe as secondary objectives, or possibly as powerups (temporarily move faster, temporarily become invulnerable, etc.).