That was fun but difficult.
It was really hard to figure out where enemies were relative to my position. I think the distance and angle of the camera was messing with my depth perception.
I think you should add shadows under the enemies so their position in the world is a little more obvious. You should also add an aiming laser so that the player has a better chance of landing their shots. A lot of times it felt like I was aiming right at the enemies but my shots were completely missing.
Ignoring those issues, the gameplay was really fun and has a lot of room for new features. Different types of enemies, weapons, platforms, hazards, etc.