A demo for Sonic Generations will arrive on Xbox Live Arcade and PSN tomorrow (June 23rd), letting players sample the 'classic style' of the game's first act, Green Hill Zone, reports Andriasang

The demo is only available for a short time, however. After 20 days it will be removed from both stores, with the demo expiring.

This poses a problem for PS3 owners in Japan, where PSN has still not been restored. If the problem hasn't been remedied by July 12, the day the demo expires, Japanese PS3 owners will not get the opportunity to play it. Of course, SEGA could extend the life of the demo in Japan.

Sonic Generations celebrates 20 years of Sonic the Hedgehog, letting players take control of classic 1991 Sonic as well as the lanky modern day hero he has become. SEGA has promised it'll deliver the 'definitive gaming experience' to Sonic fans old and new.

Sonic Generations releases November 11 for Xbox 360 and PlayStation 3.