The nintendo DS is the next in the gameboy with touch screen and a microphone with voice recognition and wireless connection and you only need one game to play mutiplayer so you have to download the game if you don't have the game  family and the sucess of the Gameboy Advance but the PSP may be a big challenge and the Nokia N-Gage QD may be another challenge as Nintendo hasn't had it also comes with a microphone and a 100metre wireless link and a touch screen screen which will be used as a maop mainly but can be used to send handwriten messages and pictures any challenges handheld wise except the N-gage