Sega's next Sonic game, Sonic Generations, will let you play as classic, sidescrolling Genesis Sonic or as modern, control-him-from-behind-in-3D Sonic. You'll control either Sonic in levels inspired by three eras of Sonic games, from the originals, to the Dreamcast era, to modern times.

No special powers. No playable friends. Sonic Team is doing development.

On Friday, I played new versions of the original game's opening Greenhill stage , testing the classic and modern Sonic variations. As Classic Sonic, I ran from left to right, running and dashing. As modern Sonic, I was playing a three-dimensional game, running, jumping air-dashing, building a boost meter and tricking in the air. Both experiences were fun and felt true to their routes (though beware, reader, I grew up with a Super Nintendo, not a Genesis).

Sonic Generations will be out later this year for the Xbox 360 and PlayStation 3. A Sega rep told me there's no Wii version because the game is fully HD. Odd. Sonic's been a star on Wii. They must have something else planned... (Sonic as a Vitality Sensor launch game? Make it happen!)

See the new Sonic Generations screenshots in the video above.

UPDATE: And here's the first gameplay trailer...