#4 Metro 2033
Image Credit: Electricblueskies
Metro 2033 is an underdog. We almost didn't include it in this list, but were it not for the fact that it was developed by a little known Russian studio with arguably limited resources in comparison to every other game on this list. They made do with what they had, and it came out better than anyone could've expected.
Metro 2033 may not have the best animations or the best textures, but I'll be damned if it doesn't have one of the best post-apocalyptic environments to ever grace a computer screen.