I am working on a huge project called Alone, a game where you are one of the 100 people left on earth after an apocalypse. The player's mission is to find who caused the apocalypse, because he is still out there.

This game is not a ZOMBIE apocalypse game, more of a nuclear one. No guns are going to be added, as this is more of a strategy… horror-ish game.
Does anyone have any suggestions?

Do the other humans interact? Maybe you could go around asking others if they saw anything? I'm unhelpful, I know, but mainly what I wanted to say is how awesome of a game this sounds Good luck on it!

That sounds like a good idea.
So, I might add a few people per level. This game is going to be a result of a bunch of experimental games, like my BloxDodger game.