Inside a large oil drum, Eggman uses an electromagnet to assemble a huge mech out of scrap metal. The fight begins with the mech climbing the inside of the oil drum with crates falling on Sonic, Tetris-style. Some of the crates contain spikes and some explode after a countdown. After receiving enough hits, the mech climbs out of the drum and Sonic and Tails must use the Rolling Combo to hit its feet before hitting Eggman's cockpit one last time.
The way the crates fall is similar to various puzzle games (often considered to be a reference to Tetris).
Sonic and Tails battling the Egg Scrap Mech, with the power of Tetris