According to several sites Rouge the Bat was added to the Sonic game in 2001 when the Sonic Adventure 2 games was released. She can also be found in Sonic Heroes and Sonic Rider games as well.
The first game called sonic the hedgehog from 1991
Sonic made his first appearance in a game in 1991. Sonic was born on day 162 of the year 3220 on the Planet Mobius
1991
2005
LittleBigPlanet was a game of the year and is considered to be better than Sonic Generations
1991 was when the first Sonic game came out
sonic began in the year 1991 SEGA released he game sonic the hedghog at June 23 then shipped it to Europe and America
First game was made in 1991
according to SEGA, Sonic is never a day over 15 in the games, but if you were to base it on the year the game was made, he would have been 12.
As in the storybook series, possibly. As for in general, there are a few in the works now, Sonic Colours and Sonic the hedgehog 4 are due to be released this year.
November 24, 2008. (a year's waiting for an answer - sorry!)
So far, SEGA is set to release two Sonic games this year, Sonic: Lost World and Mario & Sonic at the Sochi 2014 Olympic Winter games.