Why hadn't I heard of this one before? It's very good, I like it a lot. The music fits very well, until it climaxes and gets a bit too loud. The grappling hook is very fun to use!
The game is perhaps too big for a game jam, but I could totally see myself playing a full, fleshed out version.
I'll say that it's hard to notice the spikes sometimes and I'd enjoy if some of the bigger and more challenging rooms would not spawn you at the entrance every time.
Still, great game! I enjoyed it a lot.