Excellent game overall! Here's a quick compilation of my thoughts.
- I love the main menu screen, especially the zoom into the door - the art is really solid overall.
- The tutorial is well-integrated, but I feel like explaining that you move with WASD and jump with W would be nice (especially jumping with W - that took some getting used to.)
- While I think the tutorial was well-structured in general, I feel like the fact that the player only ever has JUST enough lives to complete a level can really make things frustrating while you're getting used to things, since any mistake at all effectively forces a reset. The levels being short and restarts being quick certainly helps, but it still got annoying. Obviously this is fine for later levels, but for when the player is just getting used to things, having an extra life might be nice.
- The acid hitbox feels a bit too high up, I often ended up just barely nicking it and dying when it didn't feel like I should have.
- I really like the laser mechanics! That said, level 4 in particular didn't use any death mechanics, so it kind of felt a bit out of place. Perhaps there could be some way to turn a corpse reflective?
- On level 7, you can point a laser at your own spawnpoint and kill yourself several times instantly.
- I got stuck falling on the side of a block on the first level, by squeezing in a crack between the blocks and the acid.
- Specifying that the pressure gates can be opened by blocks and such as well as corpses could be nice?
- I really appreciated being able to both push and pull blocks, that really opened up a lot of nice tricks and was generally convenient.
- Thank you for making the button hitboxes so large!
- Great work on the buoyancy mechanics, but sometimes it led to frustration with the boxes floating out of place.
Overall though, I really like the concept! I feel like there's a ton you could do with the idea - I only played up to level 7 or so, but I assume there's plenty more to play. Great work!