Sonic Generations

Sonic's birthday celebration is disrupted by a mysterious creature that pulls him and his friends into interdimensional portals. This creature is causing chaos in the time-space continuum, and Sonic must join forces with a younger version of himself to restore his history, save his friends, and fix the flow of time.

The game features two types of stages: Acts. Act 1 is played using classic Sonic, who has only three abilities: run, spin jump, and spindash. These stages are always side-scrolling platform stages. Act 2 stages are played using Modern Sonic, who loses the spin dash but gains a homing attack and can boost forward at extremely high speeds. Act 2 stages switch between 2D and 3D platform sections as they progress. Both Sonics can earn new abilities such as quicker stopping or new types of shields.

Each Era includes a one-on-one battle against one of Sonic's rivals, and culminates in a reimagined version of a classic boss battle. Completing stages also opens up challenge stages centered around specific side characters or gimmicks. Each main stage has collectable Red Star Rings to find. Collecting Red Rings and completing challenges will earn access to new music and original concept art from across the series' history.

The game features three "eras", each with three stages, which are taken from different games in the series