I don't think I can come up with a list of 10 but I'll give it a go.
1. Last Half of Darkness: Society of the Serpent Moon
2. Baron Wittard: Nemesis of Ragnarok
3. Portal 2
4. Blue Madonna (Carol Reed)
5. Limbo
6. Alice: Madness Returns
7. Conspiracies 2
8: Drawn: Trail of Shadows
9. Trine 2 (which I haven't finished yet, but so far it's really great)
10. Black Mirror 3
You can tell it's a slow year when Black Mirror makes the list
But I thought the top 5 were really fantastic.
Unfortunately I didn't find Alpha Polaris, BOUT or Deus Ex particularly memorable, but they were all okay. Skyrim didn't seem very compelling but I only played for a few hours on a friend's PC. There are so many more I need to play: LA Noire, Witcher 2, Gemini Rue, Stacking. I haven't played Arkham City but if it's anywhere near as fun as Asylum, it will be great.
Was Gray Matter really 2011? It seems older.
