Cool game idea and well done! The presentation is very polished.
I think the core concept here works, but I think you could put more focus on the jumping. There were a lot of really fun moments of being able to jump over groups of guys. Forcing a double jump felt weird here. Why not just make the base jump higher? The potion effects, while intentionally random, had either minor impact on gameplay, or catastrophically bad. Getting a gigantic knight in your way could really kill the game pace, especially if your big sword attack wasn't ready.
Congrats on completing this. I enjoyed my time with it :)