|This location exists primarily or exclusively within the Archie Comics continuity.|
Information in this article may not be canonical to the storyline of the games or any other Sonic continuity.
Sigma's Fortress is a location that appears in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics. It was the base of operations for the Maverick leader Sigma just prior to his taking over the Lost Hex.
The Maverick Hunters launched massive offensive on this location in an effort to destroy Sigma once and for all, with X penetrating the fortress while Axl and Zero engaged Vile. However, Sigma had been prepared for the attack, and proceeded to beam himself through a portal to Sonic's World. Fortunately, Silver the Hedgehog arrived to help Axl and Zero halt Vile in his tracks, and he then assisted the heroes in opening another Genesis Portal to pursue Sigma. However, despite using Sigma's own device, Silver's lack of experience opening Genesis Portals resulted in the trio of Hunters ending up in the Sonic Boom World.
After Xander Payne reset certain events, X found himself attempting to stop Sigma again, this time seeing him get shot before he had the chance to escape through a portal. With this, X, Zero and Axl felt relieved at their simple enough victory.
- Sigma's control room contained the frozen remains of Blizzard Buffalo and Chill Penguin; this is similar to how they appeared in the level controlled by Frost Walrus in Mega Man X4.