Interesting concept, I also had similar idea but didn't implement lol. I like speeding time while replaying to avoiding the misuse of this mechanic and to really make the player think. Usually I do not like game with time limits (this is why I went with step count instead of regular time in my game) as it makes me stress, but you had generous 30 min time limit, so that was fine with me. Also I always appreciate when game uses up arrow for jump too, which your game had :)
Brilliant game.