I think there's a good start here. It's very WIP, but it's a solid foundation.
This works well as a mechanics demo. There are a lot of platformer mechanics in here and all of them seem to work pretty well, movement is solid, and there are even some neat visual effects on display. The level seems to be set up to let you explore the various mechanics, though as someone coming in from the cold I was sometimes confused as to what was supposed to be used where.
This works less well as a complete game, though (correct me if I'm wrong) that isn't the intent. The level is a confusing maze, and I have no idea what the goal is. The UI is confusing; it's not clear what each bar means in the game itself. I'm not entirely sure what's an enemy and what's friendly, what damages me and how to damage enemies.
But again, it's a demo.
I think the one real criticism I have is that this is described as a speed-based platformer but that isn't really evident from my experience with the demo. I didn't really feel any need for speed and there didn't seem to be any advantage to zooming around versus moving carefully.
I think if there's one thing to improve for a second demo, versus a complete game, it would be reworking the level and possibly the mechanics to emphasize speed and to push the player to utilize all the mechanics on display.