There’s an elegance to the penalty structure that maybe wasn’t fully apparent at first, and as Tom pointed out the checkpointing is really clever.

I’m still not sure of the use-value in having that early series of rooms that all share a timer. I don’t think that concept gets picked up again later (though I may have missed it) and the result is simply that a death in any of those rooms means you’re wasting your time if you don’t purposefully fail your way back to the start of the series (since death in those rooms don’t reset the timer).

I’m also pretty sure there were times when the game wasn’t registering a direction as held-down if you’re already holding that direction before getting sent back to the prior room. (I think this is a GameMaker flaw, and that using keyboard_check_direct instead of keyboard_check would bypass it?)

Lastly, there’s one room in what turns out to be the final series that I think is too rigorously timed. It’s the second in the series, and it’s satisfying the first time puzzling through it, figuring out what to do vis-a-vis the blank stripe on the right, but on repeat it’s a boring room that nonetheless requires perfection from the player. The solution, I think — since upping the time limit would probably ruin that initial puzzle aspect — would be to remove a single ceiling block from the left side of the passage leading to the timer-reset circle. This would let the player have some leeway for exactly when they press jump there without, I think, ruining anything the room is aiming for.

In any case, I really enjoyed this. (So I’m glad Merus’ comment making the up-arrow complaint reminded me to return to it )