To avoid spoilers, press Evert button to continue.

I strongly advise that you follow the above link, download and play the game before reading further.

Sounds - possibly musical - heard in the night from other worlds or realms of being

Eversion is a cutesy Lovecraftian Freeware platformer from Zaratustra Productions, made for TIGsource's Commonplace Book Competition.

The basic premise is that of any platformer: you control a little flower guy named Zee Tee; move around, go right when possible, jump on enemies' heads to kill them. The plot? "There's a princess. Go rescue her1." The game gains a slight puzzle element: you can "evert" in certain places, changing the world around you. This might remove some obstacles, but add others, allowing you to reach previously inaccessible places.

Warping reality: never a good idea, kids. As you evert your way further and further through the game, things mellow out. Then start to get a little creepy. Eventually, the bright land you started in is but a distant memory, and the world around you is a decaying, thorny wasteland of horrors. It is up to the player whether to take this as a consequence of your reckless eversion, or discovery of the world's true nature as you peel back a false veil of brightness that overlays reality.

There are 7 levels, and 7 worlds2 - you complete levels, and evert between neighbouring-numbered worlds. That is, from 1 to 2, or 2 to 3 (but not 1 to 3). You can evert only at certain locations in each level, which allows for back-and-forth puzzle solving - particularly for those trying to get 100% completion (There are gems. You can collect them).

The game has a strong balance of gameplay and theming. The puzzles are fairly easy, enemies are threatening without being unbeatable (though the evil hands are pretty annoying), and dexterity challenges are few and manageable (in previous versions, this was not always the case). Overall, Eversion is a very playable game; I'd recommend it (though not for children or those of a nervous disposition).

1 - This is in the readme file, if you were wondering
2 - Well mostly. Collect all the gems for a Secret Ending! (With secrets!)