The concept is pretty cool! I love that you can have certain number of lives to use per puzzle and that it's not a mistake to use them. The only bit of frustration was the first time encountering bigger mushroom guy that had more than one health. I was having issues trying to dodge then explode, but sometimes the enemy recovery seemed too short to get a full fuse off on them. I eventually got it by just making sure to bait twice and that seemed to work! The upgrades were cool good job on the design there. I also wished the coins would magnetize to you if they were dropped by an enemy. Lost of lot of coinage because of that.
You are forced however to get all the health upgrades or you could be locked out of completing the final encounter. This is a design choice of course. But this would force the player to know ahead of time that they need to make sure to purchase enough health to beat them. Neat concept, but I'm not the biggest fan of that style of design.
Overall tho I enjoyed the concept and thought the game was good!