Very good game, the whole way it "feels" when you play with both the puzzle solving aspect of a slider game and the adrenaline and skill component with fast movement and (optional) times to beat worked well IMO.
The only minor thing is for Gauntlet mode: some levels the text to press a button to start playing blocks your view of some of the level so you can't plan before starting, and it would be nice to have numbers on teleporters to know where you'll end up. Most players probably won't care since it's easy enough to plan after starting the timer and experimenting and then reset to go for a serious run if you want, although I'm surprised that you let people reset the level in Gauntlet mode if they bork it up.