Eggman Empire Fortress

The Eggman Empire Fortress (エッグマン帝国要塞 Eguman-Teikoku Yōsai?) is a location that appears in Sonic Forces. It is a colossal fortification on Earth that serves as the Eggman Empire's supreme military headquarters. Near the end of the War to Take Back the Planet, the Eggman Empire Fortress served as the site for the final confrontation between the Resistance and the Eggman Army.

The Eggman Empire Fortress serves as the location backdrop for the final stages in Sonic Forces.

Description
The Eggman Empire Fortress is located in a barren gray wasteland that has similar-looking mountains surrounding it. In the center of this region lies the Eggman Empire Fortress itself. This high-tech fortification is located in the middle of a deep crater whose edges are surrounded by high walls. These walls extend into the depths of the crater, forming staircase-like levels, and the paths around the fortress consist of bridges through metallic canyons that are fortified with lasers, missile launchers, and robots. Rising up from the center of the crater is the Imperial Tower, a massive high-tech tower with tall metallic pieces forming hoops circling around it. The fortress also has several floating platforms.

In the innermost part of the fortress, below the Central Tower, lies the main reactor for the Phantom Ruby, powered by three Phantom Ruby prototypes. This reactor is hidden behind a defense system too tough to be broken through by normal means.

Past
At some point, Dr. Eggman conducted experiments on Infinite in the Eggman Empire Fortress. These experiments resulted in Infinite being fused with the finalized prototype of the Phantom Ruby, giving Eggman a servant that allowed him to conquer over 99% of the world.

Sonic Forces
In Sonic Forces, Dr. Eggman began setting up his final plan to eradicate the Resistance at the Eggman Empire Fortress, resulting in his headquarters in Metropolis being undermanned.

Eventually, the Resistance launched an all-out attack on the Eggman Empire Fortress in an effort to reach the power source for the Phantom Ruby that was located in the fortress' reactor.[4] Upon their arrival, the Resistance met the Eggman Army, consisting of hundreds of replicas, led by Infinite. What followed next was a massive battle, with the Resistance's infantry fighting the replicas on the ground, and the Resistance's air fleet engaging the Eggman Fleet in the sky. When Infinite grew annoyed by the opposition, he went through with Eggman's plan: using his powers, he created a virtual sun above the planet that would crash down and destroy the entire Resistance in one fell swoop. However, using a forgotten Phantom Ruby prototype, the Avatar neutralized the sun. With that, the Resistance and the Eggman Army resumed their battle.

As the battle raged on, Sonic and the others broke into the Eggman Empire Fortress to defeat Infinite while he was weak from creating the sun. The Resistance fleet did what they could to cover the heroes, but eventually had to retreat. In the end though, only Sonic got to confront Infinite. Just as Infinite regained his full power however, the Avatar came to Sonic's aid. Together, the two heroes beat Infinite, who faded away after his Phantom Ruby was pulled into the fortress' reactor. After that, Classic Sonic helped the Resistance locate a way into the fortress. Using this passage, Sonic and the Avatar found the fortress' reactor and destroyed it, seemingly ending the Phantom Ruby. However, Eggman soon after reappeared in a Death Egg Robot and revealed that the fortress' reactor was just a decoy; the real Phantom Ruby had been incorporated into his Death Egg Robot, which was now producing thousands of replicas, which were overwhelming the Resistance. However, Sonic, Classic Sonic and the Avatar were able to destroy the Death Egg Robot and the Phantom Ruby. This made all the replicas fade away, ensuring the Resistance's victory over the Eggman Empire. In the aftermath at the Eggman Empire Fortress, the Resistance bid farewell to Classic Sonic as he returned to his own world, before setting out to clean up the mess Eggman had left the world in.

Points of interest

 * Imperial Tower
 * Mortar Canyon
 * Iron Fortress
 * Final Judgement

IDW Publishing
In the Sonic the Hedgehog comic series published by IDW Publishing, the Eggman Empire Fortress is a location on Sonic's world. Its past is virtually identical to its game counterpart's up until after Sonic Forces.