Mario has been always the star in the Mario Games, and his brother, Luigi has been in the back; but he has gained many fans over the years. His first appearance was in the Arcade Mario Bros. Then as a part of Super Mario Bros. 3 in 1989; and last year in Game & Watch Gallery 3.
Luigi's REAL debut was in Super Mario Bros. when he was the other player in the 2-player mode, where when Mario lost a life it was Luigi's turn. Then in the Super Mario Bros. 2 you could select Luigi as a playable character, and in Super Mario Bros. 3 it was back to the multiplayer scenario as in Super Mario Bros.
Luigi did not appear in any of the Mario Game Boy game series, Super Mario Land. The only times Luigi has been on the Game Boy was in Super Mario Bros. Deluxe, and Mario Golf on the Game Boy Color.
Luigi was in the SNES game Super Mario World. Luigi was also in Super Mario All-Stars where it had all the previous Super Mario Bros. Games in one package. Then Luigi was back in Super Mario Kart, the first of the many 'Mario Team' games got underway. There was a game called 'Mario is Missing' for the SNES which happened to star Luigi. Luigi has appeared so far in 5 games on the Nintendo 64, in the 'Mario Team' series of games.
Luigi has never had a game of his own. He has been a very important character. Soon will be seen Luigi being in the game coming up Super Mario Adventure, and Super Mario Dolphin.
But who knows, when will he get his own game?