1. Metro 2033 - I found Metro 2033 to be superior to Singularity, but both games feature a good story, graphics, atmosphere and...Russians..in abundance!

2. Bioshock Series - Singularity's dark and kind of gloomy atmosphere (with lots of usage of blue and green, the "sea colors") will remind you of Rapture. Yes, the gameplay mechanics of Singularity are very similar to those of Bioshock so you will be enjoying the fun three times as much (of course, playing all three games - B1, B2 and Singularity).

3. Stalker Series (PC ONLY) - You want a game that offers more than Singularity and Metro 2033 combined? Try the Stalker series - one of the best PC exclusives ever (with all the mods of course).

EvilSelf...