The dry plains of the Mirage Saloon Zone apparently lead out to the sea, for Sonic, Tails and Knuckles now find themselves scaling slimy oil refineries off the coast of West Side Island. Like the original, the Oil Ocean Zone is an industrial area for extracting and processing oil. The entire region is a sea that has been blanketed by oil, and is being overcast by an orange sky with a lit horizon. Only some clouds and the obscured sun can be seen in the sky. The areas with solid footing consist exclusively of a network of metallic oil platforms and factories emblazoned with the Eggman Empire's decal, most of which are disposing oil into the sea. Along the roads are sections in purple and green with strange-looking ornaments.
After defeating the Meter Droid, the entire Zone goes up in flames and the region becomes darker: the sky turns dark red, the oil pools become more frequent and the oil platforms' structures become more like buildings.
After literally shooting themselves to Oil Ocean Zone, Sonic, Tails and Knuckles find themselves once again in search of Dr. Eggman to stop him from abusing the Phantom Ruby. Making their way to the most polluted region of the Zone, the trio overcomes another one of Eggman's attempts to crush them. Having not stopped Eggman yet though, the trio continues their search, which takes them to a familiar location.
When standing in the oil pools in this Zone, the playable characters will slowly sink into them; stay in them for too long without jumping and they will lose a life. The oil pools can as well be set ablaze by fire-based objects, like the Fire Shield or a Gohla's fireballs. This will create a field of fire that can damage the player should they touch it without protection, although the fire will go out after a few seconds. Some edges also have yellow outcrops that crumble a second after the player touches them. There are also oil falls in the foreground that the player can climb by entering them and then continuing to jump inside them.
Among the gimmicks in this Zone are elevators that can take the player up or down, and oil slides that the player will ride automatically once they touch them. There are also green flame-propelled gas-burn platforms that get catapulted into the air periodically, which the player can hitch a ride on. Some green pipes have as well as spikes that slide along them.
A recurring effect in the second Act of this Zone is that the screen will gradually turn more and more smoky as time passes, making it harder to see enemies or obstacles, and navigate the surroundings. Should the air become too smoggy, the player character will begin to lose Rings gradually (similar to a Super State), though this effect cannot kill the player character. To clear up the air, the player must grab and pull chain Switches that hang from the ceiling. However, this effect is only temporary. The second Act also features springs that must be pushed back by the playable characters before they can launch them forward.
The second Act features submarines that act as mini-levels within the course of the Act. Entering one will require the player character to complete a brief platforming section within before exiting into a different part of the main Act.
Like in the original Oil Ocean Zone, this Zone features networks of Cannons that throw the player back and forth around the Zone, and fans that can blow the playable characters away or take them through the air.
Act 1 is almost identical to both acts of the original Oil Ocean Zone in Sonic the Hedgehog 2, albeit much longer. One big difference is the presence of the Fire Shield, which will force the local oil to combust. Beating the boss of this Act will set the entire Zone on fire, bringing the player to Act 2.
In Act 2, the player must keep pulling pulleys under a time limit to prevent the Zone from filling up with deadly gas. This Act also features prominent use of submarines, which will take the player into the oil (and as a result pausing the gas effect). The players must navigate these small submarines in order to find the exit which will launch them to further parts of the Act.
The boss of Oil Ocean Zone Act 1 is the Meter Droid, a floating utility robot with a large spanner. This robot will fly back and forth and toss its spanner before eventually going into the background and turning a release valve in an attempt to launch the playable characters into the spike-lined ceiling. The boss can only be damaged when it is in the foreground. After six hits, it will be defeated.
The boss of Oil Ocean Zone Act 2 is the Mega Octus, a large submarine shaped like an Octus that is piloted by Dr. Eggman. The machine's main method of attack is to submerge two of the three available platforms (forcing the character to jump to the third platform or descend into the oil), summon bullet shooter tentacles, deploy a snake-like object that flies at the player, and fire a laser cannon. Hit the Mega Octus eight times to end the battle (destroying the bullet shooters can be done too but it does not contribute to the victory condition of the battle).
- Oil Ocean Zone features several references and Easter eggs:
- The Meter Droid in Oil Ocean Zone Act 1 is similar to Hei Hou from Mushroom Hill Zone in Sonic & Knuckles.
- The fire animation that occurs after beating Oil Ocean Zone Act 1 is very similar to the one that occurs after clearing Angel Island Zone Act 1 in Sonic the Hedgehog 3.
- The pull Switches used to relieve the smog in Oil Ocean Zone Act 2 is similar to a mechanic in Sandopolis Zone Act 2 in Sonic & Knuckles, in which the player must also use pull Switches to turn on the lights in order to keep the Hyudoros at bay.
- The jumpable oil waterfalls in Oil Ocean Zone Act 2 are similar (both in appearance and function) to the sandfalls from Sandopolis Zone in Sonic & Knuckles.
- The Gohla, an enemy that appears in Oil Ocean Zone Act 2, originates from Hill Top Zone in Sonic the Hedgehog 2.
- The submarines seen in Oil Ocean Zone Act 2 are based on the cruise ships from Marina Madness in Knuckles' Chaotix.
- The Mega Octus' attacks in Oil Ocean Zone Act 2 are taken from Submarine Eggman II, the boss of the original Oil Ocean Zone in Sonic the Hedgehog 2.
- The two swaying tentacles during the Mega Octus' boss fight in Oil Ocean Zone Act 2 are taken from the boss fight against the Heat Arms, the mini-boss of Lava Reef Zone in Sonic & Knuckles.
|Oil Ocean Zone Act 1||Tee Lopes||0:49|
|Oil Ocean Zone Act 2||Tee Lopes||1:02|