Love the concept of this platformer and it feels like there's a lot more you could do with it. Ended up getting the gold trophy on my second try. Glad you were able to complete your first game here and hope you'll keep working on this game to see where it goes.
I was going to advise having an indicator of how many slimes the player had, but I noticed it in the top corner. I was just keeping count myself. Maybe have UI for it to where it's easily noticeable.
Great job!