Ethan Crossfield 
Doctor Doom is taking center stage in Marvel Cosmic Invasion this fall. Publisher Dotemu has confirmed The Siege of Castle Doom, a premium expansion arriving in Fall 2026 with two new playable characters and a new game mode built around Marvel's iconic villain. The release is scheduled ahead of Doctor Doom's major cinematic appearance in Avengers: Doomsday, which is set for December 18, 2026.
What happened with The Siege of Castle Doom?
The Siege of Castle Doom will be Marvel Cosmic Invasion's second downloadable expansion. Dotemu has announced the core contents, but has not yet revealed the identities of the two incoming heroes or explained how the Doctor Doom-focused mode will work. That leaves the expansion's central hook open to speculation, particularly because the mode appears to be more than a standard character addition.
The DLC will launch simultaneously on PC, PlayStation 4, PlayStation 5, Nintendo Switch, Nintendo Switch 2, and Xbox Series X/S. Dotemu has confirmed that it will be premium content, although its price has not been announced. The game's first DLC arrived in May for $3.99 and added Cyclops and The Thing. Because The Siege of Castle Doom includes both characters and a new mode, its final price could differ, but no estimate has been confirmed.
Why the Doctor Doom focus matters now
The timing gives Marvel Cosmic Invasion a clear place in the wider Doctor Doom conversation. The beat-em-up launched in December 2025 and earned a positive critical reception, including an 81 Top Critic Average on OpenCritic. Its arcade-inspired action also benefited from the reputation of developer Tribute, the studio behind Teenage Mutant Ninja Turtles: Shredder's Revenge and Scott Pilgrim EX.
Doom's visibility extends beyond this expansion. Avengers: Doomsday is scheduled to bring the character into the Marvel Cinematic Universe on December 18, while games such as Marvel Tokon: Fighting Souls and Marvel Rivals already feature or reference versions of the villain. Marvel Rivals' ongoing story has connected its events to Doctor Doom and his 2099 counterpart, and a possible playable appearance in that game remains only a rumor.
What to watch next
The most important missing information is the character reveal. New heroes are likely to shape how returning players approach the expansion, but their identities will determine whether the pack fills a notable gap in the existing roster or simply adds more variety. Dotemu also needs to show how the new mode uses Castle Doom and whether it offers a distinct structure from the base game's beat-'em-up campaign.
A specific release date, price, and gameplay footage would give players a clearer reason to plan around the fall launch. Until then, the confirmed platform list makes the expansion broadly accessible, while the Doctor Doom theme gives Marvel Cosmic Invasion a timely connection to one of the year's biggest superhero releases.
Key takeaways
- The Siege of Castle Doom is scheduled for Fall 2026.
- The premium DLC adds two playable characters and a Doctor Doom-focused game mode.
- The new characters and mode have not been identified or detailed.
- The expansion is coming to PC, PS4, PS5, Nintendo Switch, Nintendo Switch 2, and Xbox Series X/S.
- Pricing and an exact release date are still unconfirmed.
Marvel Cosmic Invasion DLC status
| Expansion | Release | Content | Price |
|---|---|---|---|
| First DLC | May | Cyclops and The Thing | $3.99 |
| The Siege of Castle Doom | Fall 2026 | Two playable characters and a Doctor Doom-focused mode | Not announced |
Expert View
The expansion is a smart way to keep Marvel Cosmic Invasion visible during a major Doctor Doom moment, but its impact will depend on execution rather than branding alone. A genuinely different mode could give the game a stronger second life, while recognizable new heroes would help bring players back. For now, Dotemu has established a strong theme and a wide platform rollout, but the character reveal and first gameplay details will decide whether this becomes essential DLC or simply timely content.
