I didn't play very far in unfortunately because I simply did not like trying to get through the cave area with how it was designed which is a shame because I really like the idea you got here and would like to see it further developed! I like the idea of having to find funny creatures and studying them to get your upgrades that's fun. I also spent an embarassing long time realizing there was a sprint button lol.
My two primary suggestions for stuff to focus on should you decide to polish this more:
- You'll want to work on sharpening the physics a bit though, the player feels too slippery for how heavy they are (my recommendation is lowering the horizontal acceleration sothe player is less likely to launch themselves directly off the edge of platforms). Jumping feels "too fast" but its hard to gauge whether that's because gravity is too heavy or the upward velocity is too much (you can tweak this as you please though, its tricky to get something that feels "just right" for what you want!)
- The cave area is too spacious without actually having anything going on in it aside from too much platforming that isn't doing anything other then "make this one tile jump under a ceiling then get pushed off by this creature who can just snipe you if you time it badly". I think that sort of platforming challenge just isn't really the right call for this sort of game (would probably be fine in other games for the record).
Keep at it! I think you got something Cool here, even if I didn't stick with it.