Set across three defining eras from 20 years of Sonic the Hedgehog video game history, the instantly recognisable environments of Sonic Generations have been re-built in stunning HD and are now playable in both classic side scrolling 2D from 1991, as well as modern 3D style found in Sonic's most recent adventures. Each incarnation of Sonic in Sonic Generations comes complete with his trademark special move, Spin Dash and Spin Attack for Classic Sonic, and Homing Attack and Sonic Boost for Modern Sonic. An innovative new interactive menu system allows for complete immersion in Sonic's universe with favourite characters and hidden treasures gradually being revealed throughout the game.

Sonic's universe is thrown into chaos when a mysterious new power creates 'time holes' which pull him and his friends back through time. As a result he encounters some surprises from his past history including Classic Sonic, Sonic as he appeared in 1991. Modern Sonic and Classic Sonic must defeat this strange new enemy, save their friends, and find out who really is behind this diabolical deed...