Excluding unguessed songs (and assuming everything is correct), only 15 is missing.
1. Portal
2. Pokemon RBY
3. Super Mario World
4. Final Fantasy IX
5. Super Smash Bros
6. L. A. Noire
7. Super Mario RPG
8. Deus Ex: Human Revolution
9. Metal Gear Solid 2
10. Professor Layton and the Unwound Future
11. Final Fantasy Adventure
12. Metal Gear Solid: Portable Ops.
13. Final Fantasy Tactics
14.
15.
16. Ikaruga
17. Xenosaga Episode 1
18. Dark Cloud
19. Soul Blazer
20.
21.
22.
23.
24.
25.
--
We'll show her the power of a dream.