FINAL FANTASY X
This is, in my opinion, the greatest game of all time. I may just be biased because it was the first Final Fantasy game I ever played, but I really think it subtlely outshines all the others.
First, the obvious one is graphics. It just looks so great. And the CGs are mouthwatering at times. I'll never forget the CG where our protagonists grinded down the cables from the airship onto the waiting walkways of Bevelle. So amazing.
Sound. Sound effects are quite believable. The music brings back so many memories for me. Some really amazing tracks highlight this one, including various compilations of the Hymn of the Faith and Suteki da Ne. One music track, Assault (played during that CG I described earlier), is my favorite FF track of all time. Number 1. This is a game where none of the music gets old for me. Even the repeating tracks of places like Luca and Mt. Gagazet stay sounding awesome all the way through for me.
Yuna is probably my favorite video game character of all time. Auron is an incredible badass. Tidus becomes likeable very quickly. Wakka throws balls at enemies. How can characters get any better?
A revamped battle system and a great leveling-up system that allows for an intense amount of customization keep things interesting at all times. Sometimes, when I finish Yuna's section of the sphere grid, I move her over to Tidus's so she can become agile and strong. And the CTB gauge at the top right of the screen during battle allows for some great strategy in the more difficult boss fights.
I don't think I've ever played such a complete game. It has everything going for it. And that's why Final Fantasy X is my #1 game of all time.
If I had made a top 15, these games would be my #15-#11.
#15 - Star Ocean: Till the End of Time
#14 - Fable
#13 - Kingdom Hearts 2
#12 - Final Fantasy XII
#11 - Final Fantasy VIII