Doctor Doom Leads Marvel Cosmic Invasion's Siege of Castle Doom DLC

Doctor Doom is taking center stage in the next expansion for Marvel Cosmic Invasion. Dotemu and Tribute Games have revealed The Siege of Castle Doom, a premium DLC arriving in 2026 with a new game mode and two additional playable characters.

The first teaser makes Doom at the heart of the new content, but stops short of naming either of the characters joining the roster. The expansion is coming to PC, Nintendo Switch, Nintendo Switch 2, PlayStation 4, PlayStation 5, and Xbox Series X|S.

The Siege of Castle Doom is the first proper look at the second DLC planned for Marvel Cosmic Invasion. Dotemu had already confirmed another paid expansion for fall 2026, but Doctor Doom and the Castle Doom setting were kept secret until the August 17 reveal.

Doom will be central to the expansion, although Dotemu has not said he will be playable. The base game follows its heroes into battle against Annihilus and the Annihilation Wave, so Castle Doom gives Tribute Games another major Marvel villain to build new content around without replacing the existing campaign.

The DLC will add an entirely new game mode alongside two characters, making it a larger addition than the game's first expansion. Dotemu has not detailed how the mode works yet, only saying it will introduce new challenges for the game's heroes and villains.

Marvel Cosmic Invasion launched with 15 playable heroes and uses its Cosmic Swap system. Players choose two characters and switch between them during fights. New additions will expand the number of possible team combinations.

Tribute Games began expanding the roster in May with Cyclops and The Thing, the first paid DLC for Marvel Cosmic Invasion. That pack launched across all supported platforms for $3.99, while Dotemu simultaneously confirmed that a second, larger DLC would follow in the fall.

The announcement came after more than 1.5 million players had joined the fight against Annihilus since the game's December 2025 launch. The Siege of Castle Doom now gives that second expansion a name and villain, with its two playable characters, new mode, exact release date, and price still waiting to be revealed.