This is in all ways at least an equal to limbo (which is a classic in its own right), and in a few even superior.
The most noticeable part is the magnificent level design: while, like most platformers, all you really do is 'go right', the design of the puzzles and story pieces are 100% believable. At no point you get the impression that things are set up because it's a video game. You make your way through abandoned factories, forests, offices and laboratories in one, seemingly unending, level. The puzzles aren't very hard but well thought out and interesting. And varied as well: some require timing, some backtracking, there's platforming, button pressing and swinging from ropes. There are also quite some underwater areas. For those interested: a bit more variety than limbo (though that isn't saying limbo was bad).
What inside offers most is a chilling experience. More so than actual horror games, the theme, music and (brutal) deaths upon failure, inside sets a tone of unease. Something has gone horribly wrong. More so than in limbo, you will meet other people, but they too are enemies that aid that unknown mystery that's going on.
It's not a very long game (2-3 hours), but the experience makes every minute count. When you are being chased by hounds or the beings in the water, you absolutely feel it in your bones. Is that worth the asking price? That's up to you to decide.
The ending...I won't spoil much, but I gotta say that it's both very weird and open ended. Don't expect an answer to the things you've encountered along the way: you won't get that. But while I do consider that somewhat of a disadvantage, the experience up to that point are ABSOLUTELY strong enough to recommend this any day of the week and twice on sunday. :-)
