It's quite a nice list, so I decided to post it. I'll update it everytime I'll finish a new one. ;)

Note: All of these games are finished without using any single cheat.

1. Return to Castle Wolfenstein

2. Max Payne

3. Max Payne 2: The Fall of Max Payne

4. Hitman 2: Silent Assassin

5. Hitman: Contracts

6. Project IGI

7. IGI 2: Covert Strike

8. Half Life

9. Half Life: Opposing Force

10. Half Life: Blueshift

11. Delta Force: Task Force Dagger

12. Delta Force: Black Hawk Down

13. Stronghold

14. Need for Speed: Porsche Unleashed

15. Need for Speed: Hot Pursuit 2 (all gold medals both in Hot Pursuit and Championship)

16. Need for Speed: Underground

17. Need for Speed: Underground 2

18. Need for Speed: Most Wanted

19. Need for Speed: Carbon

20. Counter Strike: Condition Zero: Deleted Scenes

21. Medal of Honor: Allied Assault

22. Call of Duty

23. Call of Duty: United Offensive

24. Call of Duty 2

25. Doom 3 (including the "Lost Mission" add-on from Doom 3 BFG Edition)

26. Doom 3: Resurrection of Evil

27. Aliens versus Predator 2

28. Aliens versus Predator 2: Primal Hunt

29. Half Life 2

30. Half Life 2: Episode one

31. Half Life 2: Episode two

32. Sniper Elite

33. Prey

34. Halo

35. Quake 4

36. The Chronicles of Riddick: Escape from Butcher Bay

37. Tom Clancy's Splinter Cell

38. Tom Clancy's Splinter Cell: Pandora Tomorow

39. S.T.A.L.K.E.R.: Shadow of Chernobyl (best ending, in which Strelok does NOT join the C-Consciousness)

40. Call of Duty 4: Modern Warfare

41. Crysis

42. Need for Speed: Undercover

43. Dead Space

44. Doom 3: In Hell - Director's Cut Mod

45. Doom 3: The Ultimate Hell Campaign Mod

46. TimeShift

47. Lord of the Rings: Conquest

48. S.T.A.L.K.E.R.: Clear Sky

49. Tom Clancy's Splinter Cell: Chaos Theory

50. Tom Clancy's Splinter Cell: Double Agent (best ending + bonus mission)

51. Call of Duty: World at War

52. Medal of Honor: Pacific Assault

53. Medal of Honor: Airborne

54. Tom Clancy's Rainbow Six: Lockdown

55. Crysis Warhead

56. Far Cry 2

57. Hitman: Blood Money

58. F.E.A.R.

59. Star Wars Jedi Knight II: Jedi Outcast

60. Star Wars Jedi Knight: Jedi Academy (both paths, light and dark)

61. Star Wars: Republic Commando

62. Wolfenstein

63. Chaser

64. Left 4 Dead (Theoretically, this game is never over since it was developed mainly for its multiplayer side. But I finished the campaign with bots, just like any normal FPS. Including the "Crash Course" patch level.)

65. Call of Duty: Modern Warfare 2

66. S.T.A.L.K.E.R.: Call of Pripyat (Every good ending except for Owl's, which I didn't get at all, although I did everything what was necessary)

67. Left 4 Dead 2 (The same way I finished the first one)

68. BioShock (good ending, saved all the Little Sisters)

69. Call of Juarez

70. Borderlands (With the Soldier - level 37; every mission available)

71. Gears of War

72. F.E.A.R. Extraction Point

73. F.E.A.R. 2: Project Origin

74. Diablo (With the Warrior - level 25; Didn't get a lot of quests: Butcher, King Leoric, Valor, Black Mushroom and Warlord of Blood)

75. Hellfire (With the Rogue - level 26; Didn't get the following quests: King Leoric, Gharbad the Weak, The Magic Rock, Anvil of Fury, Warlord of Blood)

76. Portal

77. Tom Clancy's Rainbow Six: Vegas

78. F.E.A.R. Perseus Mandate

79. UberSoldier

80. Aliens vs. Predator (2010)

81. Medal of Honor (2010)

82. The Chronicles of Riddick: Assault on Dark Athena

83. Legendary

84. Tom Clancy's Rainbow Six: Vegas 2

85. Battlefield: Bad Company 2

86. Tom Clancy's Splinter Cell: Conviction

87. Dark Sector

88. Call of Duty: Black Ops

89. Call of Juarez: Bound in Blood

90. Far Cry

91. Call of Duty: Modern Warfare 3

92. Dead Space 2

93. Need for Speed: Hot Pursuit (2010)

94. Burnout Paradise

95. Medal of Honor: Allied Assault Spearhead

96. Medal Of Honor: Allied Assault Breakthrough

97. F.E.A.R. 2: Reborn

98. F.E.A.R. 3 (with Point Man, level 14 - Specter)