As with other stages in this game, Spring Stadium consists of two standard Acts followed by a third Act containing only the boss fight. In Acts 1 and 2, Sonic must free captured Flickies from inside badniks, depositing five of the birds into a Goal Ring to progress between sections of the level (usually three per Act).
Spring Stadium is the first Robotnik facility which Sonic reaches on Flickies' Island, and it's built very much in the style of Sonic 1's Spring Yard Zone: a mad fusion of bouncy, pinball-y fun and spiked pits of death. Many of the spring-pads set into the floor are fakes, but others will send the blue hedgehog shooting into the air, enabling you to access high ledges or leap straight over the aforementioned spike pits. And cunning spike pits they are too; with retracting metal blades that you can just about run across safely, if you're quick. But lose your Flickies in one of them, and you'll have quite a frustratingly tough time collecting them all back.
Eggman pilots this boss contraption around the spiky arena, occasionally swooping down low in an effort to pulp Sonic with the machine's flailing mechanical arms. The key to victory is dodging round behind the doctor and spin-jump to hit him. Another way is to leap on the springs at the top of the arena, reaching a spike-filled ledge that's high enough so the player can attack the scientist even when he's up in the air.