It's likely a three-way tie, but I'll order them in the order I played them.

1. Disgaea: Hour of Darkness - Definately the most influencing game of my Middle School years. It gave me a different (though, cruel) philosophy, but also developed a majority of my personality.

2. Phantom Brave - What Disgaea had destroyed, Phantom Brave returned; my kindness and happiness. Ash was also my idol for a long time, and still has major influences over me.

3. Pokemon Heart Gold - To me, games had simply become just that; games. Pokemon Heart Gold made me feel like a kid again, showed me just what the DS is capable of, and gave me a brand new experience as well as bucket loads of nostalgia all at once. Undoubtingly my favorite Pokemon game to date.