I think I'll just put down the series of games in no specific order:

- Final Fantasy
- Chrono Trigger/Chrono Cross
- Metal Gear Solid
- Deus Ex
- Warcraft/Starcraft
- Command and Conquer (not so much Renegate)
- Aquanox/Archimedian Dynasty
- The Elder Scrolls
- Thief
- Splinter Cell
- Battlefield
- Heroes of Might and Magic (excluding HoMM 4)
- Hitman
- Operation Flashpoint
- X - Beyond the Frontier (not the sequels)

More like TOP 15 really...