The hack is built on Sonic 2's engine, which has been enhanced by both flamewing and ColinC10 to have new features. The hack is named due to the ability to control a team of characters, which is reminiscent of the more recent 3D game Sonic Heroes.
It therefore is a single ROM that offers the entire campaigns of Sonic the Hedgehog and Sonic the Hedgehog 2, either alone or together and enables the player to play as many characters such as Sonic, Tails, and Knuckles.
Sonic Classic Heroes is a ROM hack for the Sega Mega Drive / Genesis that is the result of a collaboration between flamewing and ColinC10, combining their respective hacks Sonic 2 Heroes and Sonic 1 and 2.