Had a lot of fun! It's simple yet very effective. I really like the "defend something against waves of enemies" style of games. I played a lot of dungeon defenders lmao.
The art looks really good, I think it matches the simplicity of the game. Audio and SFX are also really good!
I liked how there are multiple enemies and it's not just one type in high numbers. Adding more types like one with ranged attacks could work well! The simple attack mechanic works well for the small game, but I always love to have something extra to spice things up (or if you wish to expand the game). A dash ability that also does damage for example. Or abilities! Throwing a fireball, an AoE attack, etc. That would work wonders and really make me want to keep playing!
I also want to note that you can kind of cheese it. You can stay at the door and press space like crazy and probably you'll win. And obviously, lots of player will do this cause that's just how we work. Maybe adding something like a stun if you take damage could push you to move around trying to kill enemies before they gather up against the door.
Super cool game, would really like to see you expand on it!