The second boss of Sonic the Hedgehog (8-bit), Bridge Zone's fight with Eggman is considerably more difficult than the Green Hill encounter. Piloting an armoured submarine, Robotnik lurks around underwater, periodically popping up to lob energy balls at Sonic. A wise tactic for victory is to stand at the very center of screen and duck under the arcing projectiles, before landing a hit on Robotnik as he submerges.
This boss shows significant variations between the Master System and Game Gear versions. In the former, the fight occurs on level islands, whereas in the Game Gear version manoeuvering room is significantly reduced by the smaller screen, and the islands are replaced with sloping bridges. This can cause difficultes when an attempt to duck under Robotnik's attacks turns into an unwanted spin roll, usually sending Sonic straight back into the path of the projectiles!