This one's good, but with caveats.
The basic concept is innovative - commercial games generally don't tweak their players this way. Not surprising though considering this was originally freeware.
The main mechanic is both interesting (even if it's not entirely original) and executed well, with the level design making good use of it, and fun twists every so often. The aesthetics follow through on the premise as much as is feasible given the style and budget.
That's the good stuff, and it's good enough for the game to deserve a look, especially considering it's cheap and short.
There are however two problems, and they can be pretty big ones depending on how you approach the game - first, the platforming physics are... less than perfect, with unintuitive hitboxes, relatively low jump precision and limited air control. The issue is exacerbated by the level design, which requires high jump precision in tricky hitbox situations in several places, and the second problem, which is bad checkpointing. The player gets unlimited lives and resumes at checkpoints, which is a good decision, but the checkpoints are relatively sparse, and worse - they are usually placed at the beginnings and middles of levels, not after most difficult parts, which means that you can fail a difficult section due to poor mechanics (at least that's what it feels like) and then have to go back and redo the better part of the level, which is always frustrating.
It's worth noting that this only becomes a real problem if you're trying for the secret endings, all gems, or 100% completion, etc. - a regular playthrough should be fun, moderately challenging and mostly frustration-free for most players, so if you're playing for the experience the game will accommodate you and you'll get plenty out of it.
Definitely worth a look!