Hmmm... it looks like a nice concept of using keys with no need of save-stating. The challenges seem legit and none of them are boring and extremely difficult to do (except for the room where you have to use double key-jump. I also like this use of custom R reset system, because if you screw up at some moment and you don't really want to die, you can use it.
This hack looks decent, but I noticed that it isn't one of the extremely fancy hacks which use custom scenery and palettes.
Other than that, I liked it! Also, nice music choice!
Really nice small piece of hack - it manages to introduce the gimmick really well and there was nothing that threw me off. I like how it also includes the L+R reset system (especially when you accidentally get a random enemy on your face) (and I think I saw a walkthrough of the whole hack once)
That double key jumping got me tho :p (ironic on my end to say that when I know most of the Kaizo design aspects for years, even though I'm only legitimately skilled on a single key jump in any case anyway).