Oil Ocean Zone

Oil Ocean Zone, Act 2

Oil Ocean Zone is the seventh zone in Sonic 2.

Instruction Manual Description

Robotnik's refineries are pumping at full steam. Crude oil has turned the ocean black. Can Sonic keep his footing on the slippery catwalks and bursting steam vents?

Villains

Enemies

• Octus - Octopus enemy, levitates and fires a missile when Sonic approaches.
• Aquis - Seahorse enemy, floats around quickly, firing globules of oil at Sonic.

Boss

• Boss: Dr. Robotnik's Oil Tank
• Hits: 8

The setup here is very similar to that of Hill Top Zone, with two islands instead of three and a pool of oil instead of lava. Robotnik is in another submarine, and this time he has a few extra tricks up his sleeve. Robotnik will appear at first, float in the oil for a few seconds, and then submege his craft again. When he appears like this, that's your only chance to attack, so keep that in mind. When Robotnik submerges, a long spikey robotic arm launches out of the oil towards you. Jump or duck to avoid it, then prepare for what's next. A laser will now come out and fire a few shots at you, one of which may ignite the floor on which you stand. Observe the position of the gun to determine whether you should jump or duck.

Differences between beta and final

• The sun scrolls with the background, and is non-animated.
• Wooden balls are embedded in the ground, and can be activated by pressing a nearby switch. They will pop up and move to the left at a fixed speed. Sonic can stand on these balls while they travel. They were dropped as a gameplay element from the final, possibly because nobody could think of a good use for them, but the chambers and switches can be placed with debug mode, and both have the same behavior as in the beta. Wooden balls were seen in prototype shots of Sonic the Hedgehog's Green Hill Zone, and can be seen in this game's debug mode, but they cannot be placed.
• Two seahorse enemies are found within the prototype ROM through hacking.
• An unused, shoot-and-flee octopus enemy is found within the prototype ROM through hacking.
• The oil splashing animation is missing and oil slides have no effect on Sonic.
• A pipe in the level's background is sucking oil up instead of pouring it out.

Technical Information

0A Oil Ocean Zone level value

2CE2 OOZ Palette (0E)

CC66 OOZ layer deformation info

400C8 OOZ animated pattern load cue (4)

405B6 OOZ misc sprite mappings (empty)

420E8 HPZ/OOZ object debug list

45100 OOZ primary 16x16 collision index

47404 OOZ act 1 level layout

47784 OOZ act 2 level layout

A3364 OOZ 16x16 block mappings

A4204 OOZ main level patterns

A6384 OOZ 128x128 block mappings

E5260 OOZ act 1 ring locations

E5422 OOZ act 2 ring locations

E8DA0 OOZ act 1 sprite locations

E9214 OOZ act 2 sprite locations

Tech note

Oil Ocean's "sinking pool" mechanic was reused in Marble Garden Zone, though it's not nearly as expansive there.

In this zone, the ground is supported by numerous small pillars that extend down to the oil, but not all the way. Because of this, the player can spindash in the oil while standing against one of these pillars to go under it. In this way it's possible to travel at the very bottom across the whole stage.