Egg Rock Zone

The Egg Rock is the ninth (currently, the seventh due to Dark City's and Grand Eggship's nonexistence) and final Zone. It is the supercharged Black Rock and Eggman's true base of operations.

Overview
Egg Rock is set on the Black Rock converted to an Eggman energy facility. There are some space sections, a mashup of all the styles and a lot of lava. Being the final Zone, it is the hardest non-secret Zone in the game.

Acts
A level that relies mainly on traps to kill you. It has a diverse selection of them and introduces a ton of gimmicks. A few enemies appear here and there and a lot of aspects of different Zones appear too.

The final non-boss Act of the game. It is very hard and uses a combination of traps and enemies to expand upon what the first act threw at you and make it deadlier. The level puts your skills to the test and the beginning can be accessed from the end. It also contains a secret disco room.

A race against Metal Sonic in a technology-filled environment which leads up to a rather interesting fight against him. You must beat Metal Sonic's best time of 1:35 to battle him or you die.

Egg Rock Core Zone
A Mini-Zone and the final Boss level which takes place in the core of Egg Rock. It is merely a round arena with crumbling walls and a battle against the final boss, Metal Robotnik surrounded by electricity.

Main things
This level is REALLY hard. If your skills aren't top-notch as Sonic, you will die. Tails will find the level ridiculously easy for the ninth Zone and Knuckles' abilities are blocked by noclimb walls or put to use by use of Knuckles paths. This also introduces a lot of gimmicks.

Statistics
Enemies:

Snailer, Sharp, Jetty-Syn Bomber, Jetty-Syn Gunner, Pop-Up Turret, Antigravity Turret

Hazards:

Bottomless Pits, Crushers, lava, lasers, crumbling platforms, gravity puzzles, surprise attacks, Spikes, being sucked into space, suffocating in space, disappearing platforms

Things introduced:

Gravity, Mini-Zones, Space, vortexes, zoom tubes, lasers, 2D mode, wall-breaking lasers, appearing/disappearing platforms, use of spindash duck, Mini mode, antigravity enemies

Emerald Tokens: Five (two in Act 1, two in Act 2, one in the disco room at the end of Act 2)

Acts: Four

Status: Complete

Trivia

 * This Zone is the ninth Zone but currently the seventh due to an absence of DCZ and GEZ.
 * In 2.0, ERZ1 had no enemies.
 * This Zone introduces the most things.
 * The disco room was created as an homage to an unfinished level in "The Wizard Needs Food... Badly!".
 * The disco room is the only place in all of ERZ to contain enemies from other Zones (not counting secret ones).
 * ERZ2 is the only non-secret Act to use the Mini mode.
 * ERZ is the only non-secret Zone to use the 2D mode.
 * This is the only Zone with a mini-Zone at the end of it.
 * This is also the only Zone with four Acts.
 * This is also the only Zone with a boss with no Eggman bosses.