I bought I Am Alive when it first came out. Completed it once, never played it again.
Sadly it's one of those games that is conceived with excellent ideas but executes them poorly. It's a bit of a drag to play really, especially the stamina bar that depletes over doing anything at all.
The studio that worked on it ran in to financial trouble I think, which is why the game is so half-baked and incomplete. You can even tell the ending is just placed in the early stages of the game because they had to cut production short.
If its going cheap then it'll stave your Survival needs for a little time I guess, but don't expect much.
I downloaded the demo for I Am Alive and I had fun with it. Regardless of the scores it got, I am thinking of buying it. From the demo I played, it had that feeling that TLOU has, where you need to do anything to survive.
I've also played all episodes of the walking dead, and I loved it. I seen that you mentioned you don't want a story just gameplay, but this is definitely worth getting later on.
Anyway, if you have the money for it, I think you should get I am alive, if you haven't bought it already
I've played a portion of Enslaved and from what I remember that game is as close as resembling tlou environment wise as you can get. Heavily forested post apocalyptic world and stuff. Based from my short experience of the game I think its pretty good.