Sonic the Hedgehog 2 is a side-scrolling platformer based around speed, and the sequel to Sonic the Hedgehog. Like the original, players run through different worlds called "zones", which each have their own specific theme. There are two Acts in nearly all of the 10 Zones, and at the end of each Zone's last Act is a machine that Robotnik controls, which you must defeat to progress. The evil Dr. Robotnik wants to conquer the world. In order to do that, he imprisons and transforms all animals into robots called "Badniks". This way they can build his powerful weapon, the Death Egg. Only Sonic the Hedgehog, and his new tagalong partner, Miles 'Tails' Prower, can stop Robotnik and his army of Badniks from taking over the world.