Just finished Singularity. Really enjoyable, surprisingly narrative-rich FPS. Didn't expect the almost survival horror-esque atmosphere the game exudes. Plot was neat, involving time travel and the repercussions of altering the past. Notes and audio logs scattered through the environments helped tell the story. Environments and enemies were interesting, AI was solid, gunplay felt good (game was developed by Raven, using UE3).
Nice variety of abilities at your disposal, unlocked over the course of the game - aging/de-aging objects and enemies, creating a sphere of slowed time that can be used to slow enemies or as a shield, ability to manipulate objects gravity gun-style, and a shockwave attack that damages and knocks enemies back, and makes out-of-phase enemies vulnerable. Puzzles throughout the game make good use of the character's abilities. Game has a fairly involved character and weapon upgrade system. Uses checkpoint save system, which may not be to everyone's taste, but it's well implemented here - frequent enough that you're not stuck replaying long stretches if you die, but still adding a mild element of tension you don't get when you can quicksave/load anywhere.
Game has multiplayer modes, but no bot support that I could see. Can't comment on that aspect of the game - tried to find a match to check it out, but it looks like I was the only person on the internet playing.
Overall, game was an unexpectedly pleasant surprise. Highly recommended.