The game is pretty good. Its different variety of weapons and monsters, arcade-like control scheme, and the increasing difficulty of each wave adds to the charm. In my opinion, the game needs a little bit of in-game music and an option to select your starting difficulty. The map isn't that bad. I really like the idea of being isolated in a small place. It also adds to the challenge and the intensity of the game. Making the map bigger would otherwise lower its tension and make the game easier. That is unless it offers smaller corridors to maintain that intensity. I hope there'll be more maps like this. However, it's okay if the game is intended to only have one map.
Regardless, it's a game I would recommend 9/10. Keep it up!