Woah. This idea is really cool take on the gel gun from Prey. I really enjoy the potential and even in this game jam state I did have fun. I do find the music annoying personally.
One suggestion I could have is to alternate between tracks so it doesn't get repetitive when a player is stuck on a level (or make a track that's really long or something). I would have liked a mute button although granted I didn't manage to add it to my game too.
The movement is really stiff however. I think it could benefit from implementation of core platformer concepts like gravity modifier based off button held or even just double jumping. I felt really heavy.
The gel gun gimmick is a lot of fun, especially with the limited ammo and having to find ways to solve puzzles It wasn't very obvious at first that the things I picked up were meant to be extra ammo but when i figured it out I really like the concept. I do think the levels are a bit long. I did manage to finish playing but it was easy to lose near the end and having to restart over and was kinda frustrating. Up to you to decide if you liked that.
One major complaint I have is that the gel projectile collides with the player and that felt extremely unsatisfying. You have to fix this if you can post-jam if you intend to work on this game more. It just really dampened the experience. I think having the gel spawn where you stand and the player is propped up is a better idea. In addition, I should be able to shoot the gel where I am about to land to soften my landing on a pile of spikes. Currently it just collides with the player and the gel gets wasted and the player dies.
Overall, I think this idea has a lot of potential and you should polish it up. It's fun. I am glad I played this game. It does remind me a bit of my own entry (platformers where you have a gun that shoots a projectile you need to solve puzzles with spikes and stuff and we both didn't have time to add proper menus)
Gave 4 out of 5 stars for Creative use of theme. Might come back and add the last star depending on other games I've played although I think with the jank it's hard to recommend the final star. Still, this idea is really good take on the theme.