When the Sega Dreamcast had to be discontinued from low sales, Sega changed their plans and became a third-party publisher, announcing to make games for systems other than Sega consoles. The Game Boy Advance was the first console Sega approached, and began work on a brand new Sonic game by hiring the developer Dimps to work under the name of Sonic Team. Dimps previously worked on Sonic Pocket Adventure for the NeoGeo Pocket Color, and it's critical reaction deemed the studio qualified to do the game.
Sonic Advance returns to the 2D gameplay of the Genesis originals, having Sonic get from the beginning to the end of the stage without dying and going as fast as possible. Enemies and barriers are spread out throughout the levels and Sonic has to collect rings to keep from being killed. Every zone contains at least one hidden 'Special Spring' which will take you to the Special Stage. Completing all 7 Special Stages will unlock the final boss battle and an alternate ending.
The levels are arranged into Zones, and in those zones are two Acts. The second act ends with a Boss Fight against one of Dr. Eggman's crazy inventions. Four characters are available to replay the levels, and their different characteristics changes how to approach the level. The biggest addition is the inclusion of Amy Rose, who is the hardest character to maneuver because she is slower and cannot curl into a ball.
The game's Tiny Chao Garden featured linkability with Sonic Adventure 2 Battle and Sonic Adventure DX, both for the Nintendo Gamecube. this allowed the trading of Chao, rings obtained in both games and items for use in either the tiny chao garden featured in Sonic Advance, as well as Sonic Advance 2.
Other features included a time attack mode, as well as a 2 player mode. This had 2 styles, single cart and multi-cart play.
Sonic N is basically a port of the Sonic Advance game that was released on the Game Boy Advance except for the exclusion of the Tiny Chao Garden. The game was a launch title for the Nokia N-Gage game deck. The game itself was on a MMC ROM, so when players saved there data it was saved on the card.
The main problem people had was that it was running was a little slower than it should be as well as the resolution which was changed to be taller but not wider like the sonic games are normally displayed.
In the character select menu, highlight Sonic, and press up, right, down, right, L, right, R, right, A. if entered correctly, you will hear a chime. then select any level as Sonic, and Tails will follow him around Sonic 2 style.