The basic game mechanics are pretty fun! Especially with that leaderboard egging you on.
Here's some constructive criticism from the guy with the high score on hell:
- It's not very clear what the range on the melee weapons is. It makes them somewhat hard to use. And because the blue weapon is the only ranged weapon, I basically only use that one, regardless of enemy weaknesses.
- Enemies can spawn right next to the player, making you take damage that feels unfair. Consider adding a check to make sure enemies don't spawn within a certain distance, or perhaps just not in the same room
- It can get annoying running around hunting for the one enemy left who's just stuck in a doorway somewhere. Some kind of hud element, like an arrow pointing to the enemies left, might be a good idea
- "play again" should launch you back into the game, not back out to the menu
All that being said, I had a good time! I think with some refinement, and maybe expand on some of the elements, this could really go somewhere!