15) Skyrim Theme (The Elder Scrolls 5: Skyrim)
14) Portal 2 Ending Song (Portal 2)
13) Hell March (Command and Conquer Red Alert)
12) Tetris Theme A (Tetris)
11) Uncharted World (Mass Effect)
10) Donut Plains Theme (Super Mario World)
(I know that this is from Super Mario Kart. Super Mario Kart's Donut Plains Theme was the same, but longer)
9) Route 30 Theme (Pokemon Gold/Silver/Crystal)
8) Guile's Theme (Super Street Fighter 2)
7) Halo Theme (Halo: Combat Evolved)
6) Mario Overworld (Super Mario Bros)
5) Kirby Dream Land Theme (Kirby's Dream Land)
4) The Man with the Machine Gun (Final Fantasy VIII)
3) Zelda Overworld (Legend of Zelda: A Link to the Past)
2) Still Alive (Portal)
1) Morrowind Theme (The Elder Scrolls 3: Morrowind)