Inter-dimensional Vortex

Inter-dimensional Vortex is the main easter egg in the Call of Duty: Black Ops II Zombies map Theoretical. When it is completed, the player is awarded the "Press Start" achievement.

Prerequisites

 * Turn on every generator.
 * Kill (at least) one Panzer Soldat
 * A player must have a Wunderwaffe DG-2
 * A player must have Monkey Bombs
 * A player must have an Olympia and Who's Who.
 * A minimum of three players. One must be Samantha and another must be Samuel.

Step 1
Enter the three rooms in where the teleporters are located (the Generator Room, the Chemical Testing Room and the main factory area) and shoot each one with a Wunderwaffe DG-2. Each time this happens, a Panzer Soldat will spawn from them and attack the player. All three must be killed by the Wunderwaffe.

Step 2
Go to the Theatre where the teleporter is located in. Once again, shoot the teleporter with the Wunderwaffe DG-2. Another Panzer Soldat will spawn and must be killed by the Wunderwaffe DG-2. After doing so, the players will be teleported into a room where Samantha will start pleading with Richtofen to get him to knock some sense into her father. After he refuses, the players must kill the Richtofen zombie using an Olympia.

After this step, the song "Hail to the King" by Avenged Sevenfold will play.

Step 3
If the player kills the Richtofen zombie using an Olympia, a Maxis Spirit will spawn and steal it from the player. The spirit must now be killed as it shoots the player with the Olympia (which now shoots bolts of 115).

Step 4
The player whose Olympia was stolen will go down after the spirit is killed and the gun is returned to them. Spawning with Who's Who, the player will spawn in the starting room, where a special Afterlife-like portal sits on the wall. Going through it will yield an electric shock, and teleport the Who's Who doppelgänger to their body. Once the player is revived, one must return to the starting room and shoot the wall where the portal was with the 115-charged Olympia. This will destroy the wall, and the gun will fall into an acidic pool.

Step 5
Maxis will attempt to control Samuel, to stop the people from overthrowing him. This will turn Samuel's vision orange, and he will not be tracked by Zombies. He must then walk into the acidic pool and retrieve the Acidgat. Samuel will now hold use the Acidgat, and the Blundergat will be added to the box.

Demonic whispering will be heard by Samuel after this step. These are sped up Mob of the Dead quotes played backwards.

Step 6
The players must go to the starting room in Shangri-La and throw a Monkey Bomb up the steps into the area where the Pack-a-Punch is located. The steps will lower, and the players must go up to the top. Samuel, Samantha, Maxis, the other player(s) and Richtofen (who reveals that his soul travelled to the Aether after his death) will have a conversation and seven Panzer Soldats will spawn. The Pack-a-Punch machine in Shangri-La is replaced by a Death Machine which can be picked up. The players must then kill these Panzer Soldats.

Step 7
Maxis will appear in his human form and attempt to kill Samuel and Samantha, claiming that they "ruined his plans" (as he still believes that Samantha is Richtofen). If he successfully kills both of them, the game will end and "Game Over" will appear on the screen. If he does not kill either of them before he is killed, then Samantha will start talking.

Step 8
The Zombies' (and Samuel's) eyes will not glow, and Samantha and Richtofen start to fight over the power. Samantha wins and Richtofen is sent back to his body. The player who is playing as Richtofen will see KILL icons above the other survivors heads, and he must kill them.

Step 9
If Richtofen does not kill them, then the players must travel to Green Run's tower, where the pylon is shown to be glowing gold. Standing underneath will teleport them, and the game will end, granting the achievement. It is revealed through a cutscene at the end that the survivors (except Richtofen) travel to a different dimension where the zombie outbreak never happened.

If Richtofen does manage to kill his teammates, he must travel to Green Run's tower and stand underneath with a Wunderwaffe DG-2. The player must shoot the top of the spire with it, and the pylon will glow red instead of gold. Stepping underneath will teleport Richtofen into the future, where he is the ruler of the remaining zombies on the Earth. A cutscene will play, revealing that Richtofen killed both his teammates and the Green Run group, save for Samuel, who becomes his lackey. If this ending is obtained, the player will still get the achievement, though a different description will be available: "Stopped Maxis. Sadly, Richtofen could not be stopped."