Very nice game! It looks great and plays very well!
Not exactly sure of the speed-up mechanic, though. As the game stands, there’s really no point to it (other than for an impatient gamer). If the level had a timer of some sort, then I can see the speed-up mechanic being more useful! Maybe to beat the levels countdown, or maybe to beat your previous level time… either way, there’s nothing pushing me to use that particular mechanic at the moment.
Still, very well made game! Great work!!!