
I like the visual style you have achieved with such "simple" methods, and the level files look quite structured.
A couple of things I did not like:
* Controls. Seriously. You need to rework those. Every state the player is in has a different control-set (Walking, climbing ladder, swimming) - Pressing Q to climber a ladder and E to jump from it is counter intuitive and really hard to handle
* Speed of the game. Also a major point. It feels like everything around the player happens way too fast, except for the actions of the player itself. Players projectile are quite slow, and you can only shoot every 1 seconds, while enemys hauling projectiles at you almost every tick
* Spawn positions of some enemys, esp. after teleporting to a location. There is no way for me at the moment to play any further, because I almost die instantly the moment I teleport.
* Memleak. Maybe this is not your fault, but its really slowing my computer down after ~10 minutes of playing