Mine would be something like:
10 Call of Duty: 4. Modern Warfare.
9 Half Life.
8 Timesplitters: Future Perfect.
7 Halo.
6 Wolfenstein 3D.
5 Quake 3: Arena.
4 Counter Strike: Source.
3 Doom
2 Goldeneye.
1 Half Life 2.
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Noteable mentions: Metroid Prime, Deus Ex, Team Fortress 2, Portal, Duke Nukem 3D, BattleField: Modern Combat.
THE NETHERLANDS