Arriving in the Mystic Ruins, our heroes encounter Dr. Robotnik near Tails' workshop. After a brief battle with the Egg Hornet, Robotnik manages to steal the Purple Chaos Emerald and feed it to his Chaos monster. Once Robotnik leaves, Sonic and Tails decide to search for the other six Emeralds in an attempt to stop Chaos from growing ever more powerful. The search starts in the dangerous but fun Windy Valley.
Aboard his Egg Carrier, Robotnik sends his E-Series robots on a new objective: find and capture a unique tailed frog. As it turns out, the tail is actually a part of the Chaos creature, though how Robotnik knows of this is a mystery...
Following his adventure in Windy Valley, Sonic finds the Light Speed Shoes, granting him the Light Speed Dash technique. Prize in hand, or rather on foot, Sonic's next destination is the fun Casinopolis...