Aesthetically very beautiful. I really liked the background effects you included (the snow and Pentagons) and the glow around the player. In general, very well executed low-poly style.
Sound design is excellent. Music and SFX all feel appropriate, and the background blizzard ambient sound really adds to the atmosphere of the game.
Concept feels innovative, and definately fits the Jam Theme.
I did find the controls a bit clunky to use. I found having to press [Space] and [Shift] at the same time to do the correct jump awkward. Also, I ended up getting stuck on Level 3-3, I just could not work out what I was supposed to do.
Overall, very strong submission. Great job!