Marvel Cosmic Invasion is getting more than two additional fighters on November 10. Developer Tribute Games has unveiled how The Siege of Castle Doom, the beat-'em-up's second paid DLC, turns Doctor Doom's fortress into a repeatable challenge built around branching routes, two competing gauges and upgrades that change from run to run.
In an October 26 PlayStation Blog breakdown, level designer Kevin Chiasson described an experience designed to complement the original campaign rather than simply add another linear level. Publisher Dotemu also released a new Castle Doom gameplay trailer, showing what players can expect from the expansion. Here are the important mechanics, what carries over between attempts and what has not yet been confirmed.
Watch the official Castle Doom gameplay trailer
The newly revealed mode sends players into Castle Doomstadt, where Doctor Doom has built the Cosmic Inductor. The invention is supposed to counter Annihilus and the Annihilation Wave, but its unstable power threatens the wider universe. Players must reach Doom before the fortress's defensive systems overwhelm their team.
How does the Castle Doom Siege Gauge work?
The challenge revolves around opposing pressures. Every time enemies defeat the heroes, a Siege Gauge rises. As that meter climbs, Doom's forces become more dangerous. Filling it completely before the final confrontation ends the attempt, according to Dotemu's October 26 press release.
The heroes have a countermeasure: Reed Richards' Stabilizer. Surviving encounters, gathering Battery Cells and clearing challenges advances the Stabilizer, buying time against Doom's Cosmic Inductor and opening opportunities to strengthen the team.
The distinction matters. Castle Doom is not described as a standard timed mission with a fixed countdown. Success depends on keeping momentum, choosing manageable encounters and generating enough resources to resist the growing threat. That creates a different decision from the main campaign's familiar move-forward-and-fight rhythm.
Five types of doors change each run
Players choose where to go by selecting themed doors, and those routes determine what help or risk comes next. Tribute Games has described five categories:
- Equipment: Earn special combat tools, including force fields and energy attacks.
- Events: Enter an encounter with temporary rule changes and possible rewards or penalties.
- Heal: Recover health before facing the next challenge.
- Infinite: Obtain a power-up providing infinite ammunition or focus.
- Progression: Collect a randomized number of Battery Cells for the Stabilizer.
For a team that is barely surviving, choosing healing over a higher-risk event may be sensible. A stronger duo might instead look for equipment or progression rewards that help delay Doom. Those are strategic implications of the disclosed systems, not claims based on hands-on testing.
The developer says the mode contains more than five times as many encounters as the main game, before counting additional events, traps and hazards. That describes the encounter pool—not five times the campaign length, or a guarantee that any individual run will feature that many battles.
What are the 12 perks in Siege of Castle Doom?
Dotemu says players can earn upgrades from a collection of 12 perks by collecting Battery Cells and completing challenges. Tribute Games groups the progression branches into Offense, Defense and Tactical, with upgrades applied individually to each hero.
The studio has not published a complete named list of all twelve perks in the source material reviewed for this story. What is confirmed is their role: improving combat effectiveness and encouraging different character combinations. Failing certain challenges can impose penalties, so players have to balance the reward offered by a room against the chance of making the rest of a run harder.
That should be particularly relevant to Marvel Cosmic Invasion's signature Cosmic Swap system, which lets players switch between two selected fighters during combat. In principle, hero-specific perks could make team composition more important. The exact strongest pairings will only become clear after players can use the finished DLC.
Reed Richards' Lab adds progression between attempts
Not every benefit disappears when a run ends. By gathering Stabilizers and visiting Reed Richards' Lab, players can unlock new equipment, events and modifiers that appear in later attempts. Dotemu describes these unlocks as permanent.
The lab gives Castle Doom a progression layer beyond temporary combat buffs. A failed first attempt can still contribute to future possibilities; later runs can introduce different tools, room events or rule changes. Successfully completing a run also unlocks a new color palette for the hero used, providing a cosmetic reward for taking down Doom.
Castle environments include the frozen battlements, dangerous halls packed with medieval-inspired traps and the Tower of Solitude, where moving elevator platforms add another threat. Doom Bots and returning bosses from the base game also feature in the challenge.
Are Doctor Doom and Invisible Woman playable?
Yes. The paid expansion adds Doctor Doom and Susan Storm, the Invisible Woman, as playable characters. Doom brings his combination of technological armor and mystical skills, while Susan's abilities include invisibility and force-field manipulation. Both were announced earlier in October, so today's news is primarily the deeper explanation of their new game mode—not a surprise announcement of two additional heroes.
In multiplayer, the developers also plan an MVP display highlighting players' performance statistics during runs. Tribute Games has described Reed Richards guiding the heroes while Doom taunts them, which should give the mode a more distinctive narrative voice than an anonymous survival arena.
The publisher additionally confirms new music from Tee Lopes, known for his work on modern retro-styled games. Specific track names and the DLC's final download size have not been detailed.
When is The Siege of Castle Doom coming out?
Marvel Cosmic Invasion: The Siege of Castle Doom is scheduled for November 10, 2026 on PC via Steam, Nintendo Switch and Switch 2, PlayStation 4 and PS5, and Xbox Series X|S. The expansion requires the base game. Steam's DLC listing also identifies it as paid additional content, but a definitive local price for every platform has not been established in the sources reviewed here.
As of October 26, the new mode is not yet available. The studio has explained its systems and supplied footage, but it has not provided evidence of how long a typical successful run lasts, the exact frequency of each room type or a final balancing assessment. Those are points to revisit when the DLC launches.
The takeaway: Castle Doom looks like a meaningful new way to play Marvel Cosmic Invasion: a branching fortress challenge where temporary build choices, rising danger and lasting unlocks matter alongside fast tag-team combat. Whether it delivers the promised replayability will depend on how those systems feel once players get their hands on it.
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Source date: October 26, 2026