The world of Angor/earth-8 is where most of the DC's doppelgangers from Marvel live. There has been various chances to saw the homeworld of the original extremists.
Justice League of America: Attack of the robots
The first appearance of Angor was in 1971. When an alien robot attacked the planet, their superheroes, the Champions of Angor attacken and went to search to whoever had sent the robots. Who they found was the Justice league, victims of the same predicament. The two teams mistaken each other for the responsible who had attacked them with the robot. After a brief fight, both teams depart to their homeworlds.
JLI: The Last superheroes.
The final destiny of Angor would be revealed by the suddenly appearance of Wandjina, Silver Sorceress and Blue Jay in earth, with a radical anti-nuclear weapons agenda. This because their own world ended in a nuclear war, leaving nothing more than a radioctive wasteland behind. The world has become so toxic than even superheroes could not endure the high radioactivity levels. Captain Speed was the last victim.
Using the magical abilities of Silver Sorceress, the last Champions, abandoned their home.
However, later, Silver Sorceress returned and a new facet of the end of Angor would be revealed: a group of supervillians, the extremists, under the leadership of Lord Havok take control of all the nuclear weapons and blackmailed the world. When the world governments did agree, the villians just drop the bombs.
When they tried to repeat their scheme on earth, they were opposed by Captain Atom and the JLE. However the JLE was defeated and send to Angor, were they were under the custody of Carny, another extremist and ruler of Wackyworld, an amusement park totally run by humanoids automatons. The fact was than even the original extremists had died by radiation poisoning, all but Dreamslayer and robotic replicas were the ones threatening Earth. The following battle against Carny woke Mitch Wacky, creator of Wackyworld and the robot technology, from his cryogenic sleep. After the shock to discover than his world was gone, he returned with the JLE to earth and stop his creations.
Justice League Quaterly: What if?
A new peek of Angor would be seen in JLQ # 3. Mitch Wacky and Kilowog, in a risky move, traveled back in time to change history and save Angor from destruction. However, their intervention was what created the extremists, in a paradox event. They also encountered the Assemblers, who, following the comedic spirit of the JLI of that time, mock on the dramas of the Marvel characters, from the anti mutant segregation of Captain Speed, the psycological traumas of the characters, specially Bowman or the numerous nuclear origins of multiple characters.
Angor would be again present in the mini-series Lord Havok and the extremist. In a more parodic take on the Ultimates/Civil war themes which were happening in the Marvel comics at the time. It's was from this point than Angor officially became a parallel earth.
Now, the superhumans of earth-8 (called Angor instead Earth) were under martial law and assembled in a military institution, the Meta Militia, resembling the Initiative concept . Opposed to them stands Havok and his extremists. But the fate of this world would be altered with the intervention of Monarch.
New52: Multiversity & Earth-7.
Reintroduced in Multiversity, earth-8 is now the home of the Retaliators, which include characters similar to their previous incarnations but different, like American CrUSAder, Wundajin (Wandjina), Machinehead, Bug, Ladybug & Behemoth, keeping their trademarked similarity from Marvel comics characters. In the comic universe, they are characters from the publisher Major comics. Others characters from that universe include the Future Family, the G-Men, Stuntmaster and Lord Havok & the Extremists.
Also must be add than a doppelganger of earth-8, earth-7, is introduced in Multiversity. Thunderer, the doppelganger of Wundajin, recogniced some of the characters of earth-8 as "they looks like his friends but they are not them". It was stablished than Earth-7 is pretty much similar to Earth-8 in history and inhabitants, but with subtle differences. In some way, Earth-7 was an Ultimate version of "616" (classic) Earth-8.
- The debut of the Champions of Angor was made to coincide with Marvel's Squadron Supreme.
- Wackyland, the last vestige of the Angor civilization and Mitch Wacky,their frozen creator, were based in Disneyland and Walt Disney respectively. Years later, Disney industries would bought Marvel comics. Talk about life imitating art.
- Pre-New52, Angor as Earth-8 had various differences from the main DC earth, including the existence of other countries, different buildings (the White Tower instead the White House), religion (the Deity instead God), the name of the country (United States of Angor) or his geopolitical reality (Angor's USA had a bigger territory, including parts of Mexico and Canada).
- Prior to Flashpoint, The Multiversity iteration of earth-8 was hinted in Superman Beyond as from earth-6, but this must be considered apocryphal. After Flashpoint, the designation of earth-6 has been given to the "Just Imagine" Universe.