Bungie has revealed new gameplay details for Marathon’s Symbiosis update, launching December 8, 2026, across PlayStation 5, Xbox Series X|S and PC. The update introduces a permanent PvE experience called Expedition, an experimental 3v3 Deathmatch mode, the Bishop Runner shell, two weapons and substantial changes to the Perimeter zone.
The developer outlined the additions in a November 10 announcement alongside a new gameplay trailer, providing a closer look at how Symbiosis will expand Marathon beyond its existing extraction-focused gameplay. All current players will receive the update, while a free Open Play Week will run from December 8 through December 15.
One of the largest additions is Expedition, a dedicated PvE mode that allows players to explore Tau Ceti IV without encountering hostile player-controlled Runners. Its initial phase introduces a three-run structure that can be completed either solo or with a crew.
Expedition replaces the threat of competing players with dedicated combat and environmental challenges. Participants can also use Flash Boosts to modify their builds during individual runs, introducing additional customization as they progress through the mode.
Bungie describes this release as the first phase of Expedition rather than its complete implementation. The studio previously identified a permanent PvE experience as a major component of its Symbiosis roadmap, offering players another way to explore the game’s environments and pursue loot without mandatory PvP encounters.
Competitive players will receive Deathmatch, an experimental mode launching in beta. It features short 3v3 Team Deathmatch encounters in which two crews compete to earn points.
Unlike Marathon’s traditional extraction gameplay, Deathmatch does not put players’ permanent loadouts at risk. This allows participants to engage in direct competitive matches without the equipment-loss consequences associated with unsuccessful extraction runs.
Symbiosis also introduces Limbo, a dedicated social area where Runners can meet other players, experiment with equipment and practice combat.
The space includes firing ranges for testing weapons and gear, alongside a dueling pit where players can challenge one another. Limbo provides a separate environment for preparation and social interaction outside Marathon’s standard combat zones.
Beyond the additional modes, Bungie is substantially changing Perimeter, one of Tau Ceti IV’s existing explorable areas.
The updated environment features extensive fungal growth and increased alien activity, transforming the landscape and opening previously inaccessible locations. Two new playable spaces have been confirmed: Burrows, an underground environment, and Reservoir, a submerged area.
Players exploring the expanded zone will also encounter the Tick Queen, a new threat located beneath the surface. Bungie has not yet provided a complete breakdown of the encounter’s mechanics or associated rewards.
The environmental changes are intended to provide additional exploration opportunities and combat encounters within Perimeter, rather than simply altering its appearance.
Another major addition is Bishop, a new Runner shell focused on speed and close-range aggression.
Bungie describes Bishop as a fast, precision-focused robotic combatant built around blade attacks. Its introduction expands the available Runner shell options, offering an alternative for players who prefer mobility and melee-oriented engagements.
Two new firearms are also joining Marathon’s arsenal.
The V17 Flamethrower is designed for close-range area denial, giving players another option for controlling space during encounters. The Maverick, meanwhile, introduces a revolver weapon archetype with an emphasis on powerful handgun combat.
The announcement identifies both weapons and their intended combat roles but does not provide complete damage statistics, ammunition specifications or detailed balancing information.
Alongside the new content, Bungie has confirmed an Open Play Week beginning December 8 and ending December 15. During this period, newcomers can access Marathon and experience the Symbiosis additions, including Expedition, Bishop, the updated Perimeter environment and newly introduced equipment.
A separate Crew Up event will offer limited-time rewards for playing with friends across Bungie, PlayStation, Xbox and Steam networks. These rewards will remain available through December 22, one week after Open Play Week concludes.
Marathon supports cross-play and cross-save across its supported platforms. Cross-save requires linked Bungie.net and platform accounts, as well as a compatible game copy on each platform being used. Console gameplay also requires the applicable paid online subscription.
Symbiosis follows Bungie’s earlier roadmap announcement, which established December 8 as the release date for the next major update. The November 10 reveal adds specific gameplay details about Expedition’s three-run format, risk-free competitive matches, the expanded Perimeter environments and the new equipment players can expect at launch.
The update is scheduled to arrive for all existing Marathon players on December 8, with Expedition launching in its first phase and Deathmatch initially available as a beta experience.
