Bridge Zone

Bridge Zone is the second Zone in Sonic the Hedgehog for the Master System and Game Gear.

Description
As with all other stages in the game, Bridge Zone consists of two platforming Acts followed by a shorter, third Act which contains the Zone's boss (and nary a single ring). The unusual feature is that Act 2 contains automatic scroll, like Sky Chase Zone in Sonic the Hedgehog 2, which controls the rate at which you move through the level (and makes it impossible to finish in less than two minutes).

The zone, as expected, is filled with wooden bridges (some less sturdy than others), as Sonic crosses South Island's massive central river. There are also giant metal scales dotted around the level; presumably these are placed by Dr. Robotnik as scientific equipment of some sort.

Boss
Considerably more difficult than the first boss, especially if the player is playing on the Game Gear's reduced screen (not only is the maneuvering room reduced, but the fight takes place on sloping bridges rather than level islands). Robotnik takes to the water in an armored submarine, and shoots trios of energy balls at Sonic as the hedgehog jumps between islands in the river. The trick with this boss is to stand on the central isle and duck. The Doctor's attacks will pass over Sonic's head, and then he can hit Robotnik before the submersible retreats underwater. In the Game Gear version, Sonic must move to the other sloping bridge, duck, and he must try not to roll too much or he will get hit. It can actually be an easier fight here, as the player can't die by falling into the water. In fact, there is an effective strategy: simply roll into Robotnik to deal about three hits of damage at one time. When defeated, Robotnik's machine will far sink below the surface of the water, awaiting a rematch in the next water level.

Trivia

 * The background music for Bridge Zone was, years later, remixed as Tails' theme music in Sonic Adventure, "Believe in Myself".
 * In the song "Together Again" by Janet Jackson, parts of it sound like Bridge Zone's music.