Ohh.. Tetris Worlds... You see, BJW just said Tetris. And Tetris was a game on GameBoy. If he would have said Tetris Worlds it would have been much, much different.

ok how about the worst personaly i think there is not a worst they are all grate

Breath of FIre

super mario advance 2

Ecks vs sever
 

Ecks VS Sever is the best game on GBA so far cos it'll take ages to finish, there are two charecters to play as and there's such a wide range of wepons!
havent tried the multiplayer cos no one i know has a copy...

GET IT!!!

Here's another vote for Golden Sun.

can i change mine to golden sun i already have super mario world for snes and think it dont deserve to have my vote for best gba game( its a great game tho)they have to make a golden sun 2(i no they will)

Yet another vote goes to golden sun.

Cant wait for Golden sun 2: A lost age

Ok, please put in puncuation. That was really confusing for a second.

Best game - Mario Advance 2 or Golden Sun
Worst game - don't know, I have four great games, no bad ones.

That reminds me of the answer I should have gotten right in the Trivia: Round 3. ;)

Anyway, the best game for the GBA by far is Advance Wars. I believe it won the best handheld game of the year. There are so many missions packed into the game that you'll be spending hours on end trying to complete them all. There's also multiplayer with one or more carts, and you can create your own maps if you get bored with the pre-made ones.