This is easily one of the finest games I've played so far this jam, not only from a proof-of-concept standpoint but also as a properly fleshed out design. It's not uncommon to see puzzlers around here and the usual advice is simple: take one of two core ideas and execute on them well. You did exactly that here. I'm impressed, there's really no wasted space. Each mechanic is clear and intuitive and serves the others well in a really satisfying and cohesive experience.
Art: Fantastic all around! The simple, cutesy art style serves your free and breezy mechanics well, I'm definitely a fan of these lil dwarves. Not to mention that one song is an absolute banger, somewhere between a pirate jam band and tavern soundtrack that I really vibed with. One very minor change might be to keep the music playing on the death screen, just to keep the flow going, but on the whole I adored the soundtrack.
Movement: This is a crucial part to get right, and I'd say you all stuck the landing. The movement was floaty, but precise enough to be maneuverable, and the stacking mechanic was an enjoyable take on the event theme with some room for innovation and expansion. I have to give a particular shout out to your bounce mechanics and especially their integration into the level design. The first time I realized that stack height affected bounce height was a treat, a genuine moment of surprise and epiphany in a cute little game.
Interesting choice, too, not to allow for jumping. That was a big risk but I think it paid off well, keeping the puzzles focused on the core mechanics rather than on direct platforming skill.
Environment: Nothing but praise for your level design here. For the time allotted, there were some genuinely creative and exciting puzzles in this one. I appreciated the gradual scaling of difficulty and introduction of new mechanics in an approachable way. The bounce pads were certainly some of my favorites, both from a movement and puzzling angle. That early level with a set of jumps over a spike pit was probably my favorite to run.
Some of the later levels, too, made great use of the fact that dwarves higher on the stack could activate bounce pads. Early on, I wasn't sure how I felt about this, but I ended up pausing and taking a note about how much I enjoyed it and some of that more inventive level design.
Overall, genuinely great work, I'm glad you got it in before the deadline!