Sonic and Tails: Double Trouble 5i6l4n

A Sonic the Hedgehog mod that includes Tails as a playable character, new/different layouts for every stage, different music ported from other Sega games, double boss fights in some zones and new moves! 281sh

Press B (K on the keyboard on the default setting) at the main menu to play as Tails.
Tails can fly up to 8 seconds before getting tired.
Also features different level design and music.