A good game, based on a nice idea. You should make more of these nice simple games; not that I didn't like your other ones.
Just a few points, though none of them are a game breaker:
The lo-fi look is nice, but it might not be the right fit for this game. I admit I played this game while tired, but it was hard to look at when it sped up. It started to tessellate and it became hard to see what was moving. My eyes started to really spasm out around the 4th span. I think its because the floor, being such a simple pattern, stops looking like its moving, and is just a flashing grid.
The random generation of the paths is a necessary part of the game, since its supposed to be about reaction, not memorization. But some nearly impossible situations do seem to happen often. Passing the game ends up being half luck, half skill. Replaying story, I found the twitchiness I got from playing the last level didn't guarantee the first level was a cakewalk. I'd still die fairly often because of bad luck. Also, it does seem you change what sort of dungeon you'll encounter based on speed, since navigation involves different diagonal motion angles, but you don't switch up the moment you cross a speed line, which means they are often death traps as you try to navigate a path that was meant to be travelled at a slower speed.
Finally, while I realize it's sort of a nit-pick, and probably something you can't work around, but I didn't like that your jump hang-time was reduced as you began to run faster. I realize you wanted to make each jump be exactly one pit length, so you removed the ostensible advantage you'd get from longer jump distance from faster running. It would have made the game more difficult to plot, if jumps might mean you'd hit a wall further behind a pit because of long jump distances, but I felt it ruined the feeling that you were actually running faster. What actually was happening was the game was arbitrarily speeding up time to make the challenge increase. It would have felt more viscerally like running fast if it meant jumps went further, and you'd have to time the landing better, but you'd have an easier time with the starting point.
Still, overall good game, and those three points didn't take off more than a star for me.