Game was ok. Collisions were buggy and sometimes non-existent. When you start you can walk through the back wall. The gun is very inaccurate.
It seems the best strategy was to walk backwards to a distance where the enemies cant hit you, but you can hit them. The enemy projectiles homing towards the player is not a great idea as you are already limited in left-right mobility. Maybe you could have attacks, that go straight down the dungeon/tunnel, where you have to dodge left/right and jump over.
If you added some more content and polished the gameplay, it could become a fun game.