Sad you weren't able to implement more of the journey aspect of the game but I like what you have so far.
The art and the sound effects are all top notch, just love to hear fred barf everytime you beat his ass.
I'm really bad at memory games so I struggled a lot with this after many attempts I did shamefully resort to cheating by taking screenshots so I could win, please don't judge me. I just wanted to see if there was any sort of victory screen.
I think there should be some sort of continuation when you lose a heart instead of a full restart. Otherwise it's no different from just restarting the game. I imagine since you wanted to have more opponents losing a heart meant you start again from the start of your current opponent instead of the start of the game.
Other than that, a fun and well presented game. Nice work.