There are some great single players from 10 years ago that if you never played id highly recommend, added a few MP as well:
- Halo 1-3 & Reach (best with a friend, co-op mode always been the most fun)
- Bioshock 1 & 2 (my most favourite single player series)
- Metro 2033 (highly recommended)
- Metro Last Light (highly recommended)
- Dead Island 1
- Farcry 3
- Fallout 3
- Fallout New Vegas
- Fallout 4
- Call of Duty IV Modern Warfare (original) (campaign)
- Call of Duty V World at War (campaign)
- Call of Duty VI Modern Warfare 2 (original) (campaign)
- Grand Theft Auto Series
- Sleeping Dogs
- Bully
- Star Wars Battlefront 2 (multiplayer)
- Hell Let Loose (multiplayer)
- Portal 1 & 2 (highly recommended)
- Stellaris (very specific style of game, strategy)
- Dyling light 1 & 2
- Dead Space Series (highly recommended)
- Batman Arkham Series
- Dishonored 1 & 2
- Prey
- Halo 1-3 & Reach (best with a friend, co-op mode always been the most fun)
- Bioshock 1 & 2 (my most favourite single player series)
- Metro 2033 (highly recommended)
- Metro Last Light (highly recommended)
- Dead Island 1
- Farcry 3
- Fallout 3
- Fallout New Vegas
- Fallout 4
- Call of Duty IV Modern Warfare (original) (campaign)
- Call of Duty V World at War (campaign)
- Call of Duty VI Modern Warfare 2 (original) (campaign)
- Grand Theft Auto Series
- Sleeping Dogs
- Bully
- Star Wars Battlefront 2 (multiplayer)
- Hell Let Loose (multiplayer)
- Portal 1 & 2 (highly recommended)
- Stellaris (very specific style of game, strategy)
- Dyling light 1 & 2
- Dead Space Series (highly recommended)
- Batman Arkham Series
- Dishonored 1 & 2
- Prey