For a first game jam it's alright. I got stuck on the map with a black box even with the two shells combined. Couldn't figure out how to get it in the box. On the first play time the double shell stack also disappeared after I believe I misdragged it out of the crafting slot.
Perhaps adding a small tutorial on the mechanics of how things work, since I don't think the rewind did anything. Hope you learnt a lot on making a game and good luck in your future jams!