Definitely the best take on "reverse platformer" I've seen so far. I appreciate you being brave enough to let the player make their own choices, rather than dictating a solution - I think that's a much better route than forcing one solution per level. I do think you could have been a bit more forceful in the last level -  I would have made the distance between platforms less wide, so that building a straightforward staircase wasn't still the best solution. I just made a really big staircase, but it seems like it would have been more interesting to make me go back and forth between the solid platforms. That's a minor quibble, though, and this is a great game.