As per usual for the PC puzzle-platformer genre, there are infinite lives and fairly regular checkpoints. Getting through each stage is challenge #1 (and there are some very tricky puzzles), and then finding all of the hidden artifacts is challenge #2 (some of which can't be completed until you revisit levels later).
Interestingly, there are boss battles, which is unusual for this sort of game. In practice, these are just additional puzzle stages dressed up as monsters, but still, given that there's no fighting otherwise (there's no attack button!), it's an interesting change-up. Beating the bosses is also what unlocks new powers: Greater range for the green light, and access to the red and blue lights.
I had issues with the game's performance on my PC—when you're trying to make pixel-perfect jumps, having slowdown and the game not acknowledge keypresses are pretty much the worst things ever. The game definitely got frustrating; and I needed to take breaks rather than trying to play straight through. I also found it irritating that the solution to multiple puzzles was to go back to before the checkpoint, retrieve a lantern from there, and carry it to where you could use it. That's fun once, and annoying every other time (especially when you're dying constantly).
I was reminded on Eversion in a bunch of ways: Both in the style of game, the creeping horror aesthetic (which is much more gradual and subtle here, partially just because the graphics are much, much nicer) and the idea of the alternate “layer” of the world that you need to access to proceed.
Overall: I can see why this won awards; the puzzles are very good, the concept is interesting and the graphics are very pretty. That said, the platforming difficulty level is awfully high and the controls could stand to be more responsive. I'd specifically recommend this to platformer enthusiasts with high-end computers.