Awesome game, great atmosphere and the art really makes it immersive. I absolutely love the stoic look on the main character's face. Like he's perpetually thinking "I'm getting too old for this shit".
The gameplay is smooth, although the wallriding needs a little bit of tweaking. I got used to it by the end, but in the beginning I was expecting the walljump to other walls to stick even if I was holding the opposite direction from the previous wall. Currently, as soon as you hit the other wall, you immediately bounce off it again, which is only solved by switching directions mid-air. Again, 'minor' tweak with a lot of dev time needed, so it's completely understandable because of the jam.
I loved playing it, but gave up about 3 or 4 levels in, because halfway through there was a jump that was very big and felt almost pixel perfect. It felt a bit unfair given the fire that's directly below. I really tried, made it once but failed on the jump immediately after :P
Overall I think this would be a great fleshed out full game!