Well, the Mario franchise's past handheld games have been.... Less then spectacular in the past (With Mario Kart DS and Super Mario 64 DS being the exceptions), so when New Super Mario Bros. came out in 2006, I wasn't expecting much. I was wrong on so many levels. This game is not just a remake of the original Super Mario Bros. for NES, but an entirely new game with new level designs, villains, and multilplayer features.
The multiplayer on this is some of the best, with the "Mario vs. Luigi" mode that allows players to play against eachother with or without two copies of New Super Mario Bros. (Using DS Download play). Minigames are also available in a multiplayer mode for the first time since they were introduced in Super Mario 64 DS.
Play as Luigi
When you start up the game, select the single player mode. Hold "L" and "R" then click "A" on the account you want to use. When you play the game, you will be Luigi instead of Mario.