I couldn't get enough of Tommy's little victory shred, I smiled every time he got excited about grabbing a power-up. The music really set the mood, from the quite ominous opening music to the more exciting exploration track and the rocking final boss track, great choices. :D I also really liked the map, it was relevant to the theme and once I figured it out it made exploring pretty straightforward. Enemy death animations and breaking the seals were all very satisfying. And don't get me started on that ending... looking forward to the next installment!
Some places where it could be improved,
1. as others have said, the jump is a bit floaty, but what bothered me more was having to fully commit to each very long jump, you couldn't do little hops. There were a few places where you had to climb some little steps and this made those areas a bit tedious.
2. it was never clear to me if I was breaking the game by using the dash move to jump in mid-air. As I progressed deeper into the game, I began to feel more and more like this was intentional, but the first few times I did it I couldn't help but feel like I was cheating.
3. The opening area is quite small but I looped through it quite a few times before I realized I was missing the exit leading to the first power-up. I ended up having to check the map to see that there was a door I had missed, which in itself isn't really a problem, but I think a bit more sign-posting that there's an exit there as you're running through that room (maybe some lead-up platforms or something) would have helped.
Anyway, I had a great time helping Tommy escape Hell, great work! Also my final stats were 5 deaths, 24 minutes.