Really great idea for this year's Game Jam! It's pretty good, but I feel it needs more visual clarity. For example, I don't really like how the game (for the first two levels) entice you to go into the pits by putting in a chest or a character to teach you to use r to reset. It's not even a game-changing mechanic, so I don't think it needs to be "taught" in the first place. Putting a reset button (with hotkey r) in the corner is a simple yet effective way of showing the mechanic, and there's really not much to it. There's also the rotational buttons and the portals. For the rotational buttons, there really needs to be something, maybe different coloured blocks, to show the player which blocks are rotated in the first place. As for the portals, there needs to be some consistency as to which portal goes to where. The last level featured three yellow portals and it just needs to show that the yellow portals on the left both lead to the one in the air (another thing is about that level is that if you hold left when you start, you die on the spikes near the red portal, and I think that it needs to be tweaked a bit to avoid that). Other than that, I really dig the idea of a platformer using only one jump and I like how it's implemented in this game.
Thanks for playing and giving a detailed critique. I pretty much agree with everything you said. Especially coloring the rotating platforms to make it obvious what will move.
If this game were to ever be brought to to a production level, it would need a complete overhaul. Detailed feedback like this would help point the game in the right direction.