I actually played through this game this morning (only like 4 hours long and I had all day to myself)
This writer seemed to leave out that the description of the game from the xbox menu reads "Uncertain of his sister's fate, a boy travels into Limbo." You were searching for her the entire time, but the game itself won't tell you that. I understand not wanting intrusive storytelling, but a little title card at the beginning of the game reading that won't ruin it. otherwise you just think the whole point of the game is to go right.

THE REST OF THIS POST IS SPOILERS!!!!

The game doesn't "squeeze it in at the end" either. there's a part about 2/3 of the way through where you see his sister and you know you need to get to her, but you're forced to turn around and when you come back, the screen is completely different. I'm no good at symbolism and all that, but I hope there's a bit more to the ending than what's on the surface.

I'd say there is just as much genius to the barbones style story. The story has not been laid forth before you, other than to tell you that you are searching for your sister. Why exactly? Well that really is left to your imagination. Maybe its not the sister that is actually lost, maybe it's the boy. In a comma or hurt in those woods trying to find his way back to reality. The last thing he sees before whatever it is that puts him there on the forest floor is his sister and he is fighting to get back to that. The story, until the developer says otherwise, is completely left to the player to fill in.

Two games that for me are definitions of what interesting story telling in a game can truly be in one year: Limbo and Alan Wake. Good stuff.

MiSide

I’m reminded of some of the alternate endings in the Suffering games.

Wouldn't the answer here be ... all of them?