SOLVED. YA Dystopian novel about a girl taken to a habitat/dome (?) with 5 other teens. [s]

[Carina]

I read this a few years ago (maybe 2013/14). A girl was taken from Earth and I think she wakes up in a desert (not sure if that's right). I remember she walked a short ways and there was grass or snow - and another placed there was a lake with a dead girl in it. She eventually got to this weird set of buildings and one of them was a candy shop. There were four other teens there, one that she knew from Earth, and eventually a fifth girl joined them. All the buildings had little puzzles to solve that would give them tokens (I think) that they could use at the candy shop. Also, they all had a headache all the time that sometimes got worse. I remember that an alien that had metallic skin, wearing a suit with a certain number of knots in it to denote rank, would sometimes show up and stop them from doing certain stuff, and I think the girl formed a bond with him. He told her that Earth had been destroyed and they were what was left, and they were supposed to pair up and procreate to create a new population. I also remember she escaped a couple of times, once grabbing on to the alien before he teleported out, and another time buy swimming to the bottom of the lake.

This was a recent book, and I can't seem to find it anywhere. Another friend read it too and couldn't remember the name. She thought it had cave in the name or something like that. Any help would be greatly appreciated.

[Lou]

The Cage ?

[Carina]

Yes!!! Thank you Lou - this is it!