via Computer and Video Games
Super Sonic will be playable in Sonic The Hedgehog 4: Episode 1.
The giveaway comes via the game's achievements, which lists one of them as 'Golden Flash - Clear all Acts as Super Sonic'.
That's pretty cut and dry then. The old school method of turning into Super Sonic was collecting all the Chaos Emeralds and jumping (Sonic The Hedgehog 2) or jumping then pressing jump again while in the air (the others). We reckon Sega will use one of those methods to keep Sonic The Hedgehog 4 feeling as retro as possible, but we'll just have to wait and see.