Fire Emblem: The Sacred Stones (Game Boy Advance, 2005)

I really enjoy the quest/mission/rpg genres of video games, and this game is a perfect example. You begin with only a couple characters to battle with, but as you progress in your adventures, you acquire more companions to help you complete the missions. You have the freedom to choose which characters you'd like to use more and give them more fighting experience, so that you can level them up to become stronger fighters, faster swordmasters, craftier thieves, and tougher knights, among other titles. It's just an all around fun game you can play time and time again.