Golden sun 2!!!! Best game on the GBA IMO.

@Axxol said:

Golden Sun 1 & 2

@crusader8463 said:

Advance Wars and Final Fantasy Tactics: Advance.

Make sure to play Fire Emblem and Fire Emblem: The Sacred Stones on top of the 4 games above. All of these recommendations are RPGs/strategy in some shape, so if you're not into RPGs or strategy I don't really know what to tell you.

@believer258: It's an original (white) model.   Thanks for all the recommendations everyone, I'm going to have to bookmark this page and create a list :)

  I have never, ever seen or heard of a person who had a Micro. Would be cool to hear if someone actually bought one (and would be handy for a college kid on the go such as me. Wish I'd gotten one...) 

Final Fantasy VI Advance

The only game that I think should I can contribute that no one seems to have mentioned so far is Gunstar Super Heroes!

It's a real gem, though I can't imagine it's too easy to find. Also Harvest Moon: Friends of Mineral Town is sort of my GBA guilty pleasure. There's always something to do and it's sorta janky about it, but in a really Japanese way.

If you like Pokemon, any Pokemon game will do, Zelda Minish Cap  

zelda: minish cap 

  Was too busy playing tetris on my gameboy colour to even think about getting another handheld.

@JTB123: Listen, I know you're a collector and all, but drop that unit back in its box, put that box away in a closet, and get a DS Lite. GBA games were meant to be played with a backlight.

Kuru Kuru Kururin

Some of the early games of Megaman Battle Network had some really cool ideas and was a lot of fun. Advance Wars is always a good option. And Final Fantasy Tactics Advanced you can pour hours upon hours into.

Granted it's a GBC game, but one of my favorite games is Wario Land 3. I've yet to find a 2d platformer that I've loved more, and have loved coming back to more, even to this day. Totally worth tracking down a copy.