Fantastic art, reminds me of Skullgirls, such a distinct identiy. Gameplay was great, simple yet engaging mechanic, great player retention and replayability. I kept wanting to go back in every time i lost, story was charming too! I'm not particularly keen on long dialouge right out the gate when playing short games, but this one had me engaged, with its brilliant sketchy art style and very expressive character dialouge, that being said, I'm surprised you only get the fun cutscene through the tutorial, It'd be a shame people miss out of that fun little moment if they just skipped straight to the gameplay, you only get the relationship between the two protagonists and that awesome art through that cutscene.
As for negatives, I bugged out a couple times in the big reactor thing when my hammer would lock me in place and I'd be unable to move, wasn't sure what happened. Also, I noticed that when I combo'd long enough, the camera shake would be a little too powerful and made it a little difficult to see what was happening on screen.
I wouldn't call this a negative but I also noticed at the endgame with the scale being so high, it was hard to maneuver around with everything so big and the player being so small, plus no healing kept me on edge, but I'd attribute this to pretty neat difficulty scaling.
Overall that was really fun! I want to see more from these character and their wacky adventures and I found the gameplay really replayable!