Inside Castle Doom: Branching Paths and a Race Against Time in Marvel Cosmic Invasion

A glowing door can be a promise or a gamble in MARVEL Cosmic Invasion's next expansion. On October 26, developer Tribute Games and publisher Dotemu revealed the run-based Castle Doom mode, where heroes pick routes through Victor von Doom's fortress while racing to stop his latest invention.

The Siege of Castle Doom is the game's second paid expansion, scheduled for November 10 on Steam, Nintendo Switch and Switch 2, PlayStation 4 and 5, and Xbox Series X|S. It also adds Doctor Doom and the Invisible Woman as playable characters.

A rivalry becomes a clock

Tribute Games level designer Kevin Chiasson explains that the team organised the mode around the rivalry between Doom and Reed Richards. Doom's Cosmic Inductor is charging, and a Siege Gauge rises when the heroes are defeated. Victories provide batteries for Richards' Stabilizer, which helps hold Doom's progress back.

That turns a familiar comic-book conflict into pressure the player can read. Dotemu says the castle's forces grow stronger as the Siege Gauge fills, and a full gauge ends the attempt before the final confrontation.

Kevin Chiasson on the mode's design

Doors make the next fight a choice

Instead of a single fixed path, players select themed doors offering different opportunities. Chiasson describes routes for equipment, healing, temporary combat events, power-ups and batteries. Players must weigh immediate help against progress toward the Stabilizer.

The castle is more than a backdrop for those decisions. Chiasson points to medieval hazards in its halls, blizzards on the battlements and moving platforms in the Tower of Solitude. His team says the mode contains more than five times as many encounters as the main game, before counting its additional events, traps and hazards.

In Dotemu's press images, green-lit door symbols sit against stone and book-lined rooms. The contrast makes the route markers easy to spot within the dense pixel-art scenes, a visual reading rather than a claim about the artists' intent.

Each attempt can change the next

Players can collect batteries and complete challenges to earn offensive, defensive and tactical perks. Dotemu says unsuccessful challenges can weaken fighters, while successful runs can permanently unlock equipment, events and modifiers through Reed's Lab.

The expansion keeps the beat 'em up combat at its centre while giving its castle a new role: part characterful Marvel location, part sequence of choices that can reshape each attempt. The mode and its two characters are due together on November 10.

Dotemu's mode announcement