Marathon‘s Expedition is a permanent co-op PvE mode where you play a Run Series of three runs that get harder each time, building power with Flash Boosts on top of a faction loadout, with no rival players hunting you. It arrives with the Symbiosis update on December 8, 2026, and Bungie laid out how Phase 1 will work in its “Dev Deep Dive: Expedition – Phase 1” on November 12.
What Expedition Is and Who Can Play It
Bungie calls Expedition “a fully PvE cooperative roguelite mode.” It will have its own dedicated queue and run across four zones: Perimeter, Night Marsh, Outpost, and Cryo Archive.
- Squad size: solo, duo, or a full trio.
- Other crews: you share the zone with multiple Runner crews, and Bungie says you work together with them against the horrors of Tau Ceti rather than fighting them.
- Matchmaking: Bungie’s Open Play Week and Crew Up post points to crew fill matchmaking to round out a team, so you do not need a full group of friends.
- Joining late: if you join a crew already partway through, you pick up at the highest run in their chain, even the final one, but you only get your faction loadouts instead of a build curated run over run.
- Contracts: Priority Contracts can still be completed in Expedition.
You can only pick zones you have unlocked by raising your Runner Level, and Bungie says they scale in difficulty much as they do in Extraction.
How a Run Series Works
Each Expedition session is a Run Series: three runs in a row, each harder than the last. You choose the zone for every run, so you can stay on the revamped Perimeter all three times or spread out across Tau Ceti and finish on the Marathon ship itself, in Cryo Archive.
The first two runs are preparation: explore, complete contracts, loot gear to shape your build, and collect your first Flash Boosts. Bungie’s advice is to keep track of who in your crew is building in which direction before the finale.
The Critical Incident is where you can raise the difficulty floor to reach tougher activities. Bungie names three: solving Upper Complex in Night Marsh, accessing Pinwheel on Outpost, and fighting the Tick Queen, a new enemy on Perimeter.
You can reset a series at any point in the chain, either to cash out the rewards you have so far or to start over when a build did not come together. If you survive all three runs, you choose between cashing out and rolling the series into a new one, which keeps the build you put together going so you can see how far you can push it.
Run Kits: Your Faction Loadout
Run Kits are the loadouts you start a series with. In Phase 1, each faction has its own set, each built around different playstyles and weapons.
- Your loadout is locked for the whole Run Series.
- Weapons and items can still be looted or improved during your runs, until you reset the series.
- You start on a basic faction loadout, and as you progress you unlock faction upgrades that keep improving that starting kit.
Flash Boosts: The In-Run Upgrades
Flash Boosts are Expedition’s new in-run upgrade system, and Bungie calls them the main driver of power and buildcrafting in a Run Series, apart from your loadout. You get them three ways:
- Looting them from around the zone.
- Killing a tough enemy.
- Completing objectives.
Picking up more than one of the same Flash Boost stacks them, raising that boost’s rarity and potency. With your loadout locked, they are what make one series play differently from the next.
What You Keep and What You Lose
When your Run Series ends, Flash Boosts and the other gear you picked up during Expedition are sold. Your credits and XP stay with you.
Bungie’s suggestion is to bank those credits to buy gear for your next Extraction run, and to spend the XP on buffing your Cradle. That makes Expedition a lower-pressure way to build up for Marathon’s PvP side.
How Expedition Differs From Extraction
Extraction is the cutthroat PvEvP mode Marathon launched with, where other Runner crews are a threat as well as the AI, and what you carry in is on the line. Expedition changes the rules: every crew in the zone is on the same side, three linked runs build toward the Critical Incident, you grow a locked Run Kit with Flash Boosts, and the gear you find is sold at the end while credits and XP carry over.
If you want PvP without the risk instead, Symbiosis also adds a Deathmatch beta. For a different approach to PvE in an extraction shooter, our guide to ARC Raiders’ PvE mode covers how Embark handles it.
What Phase 1 Means and What Comes Next
Phase 1 is the version that launches with Symbiosis. Bungie calls it “just the start”: it will reveal more about Expedition’s Phase 2 in March, then keep improving the mode based on feedback. Before launch, Bungie’s Dev Insights Part 2, due December 1, will take a more in-depth look at Expedition and the rest of Symbiosis.
Bungie’s wider roadmap, which we covered in our story on Bungie’s plans for Marathon, lists an interconnected system of permanent PvE, PvP, and PvEvP experiences for March, along with new alien combatants and an entirely new zone. Bungie has not said exactly how Phase 2 fits into that update.
When and How to Start Expedition
Expedition goes live with Symbiosis on December 8, 2026, on PC, PS5, and Xbox Series X|S, and our Symbiosis release date story lists everything else in the update. To play, pick Expedition’s dedicated queue and choose a zone you have unlocked.
- Open Play Week: from December 8 to 15, anyone can download and play the full game without buying it, Expedition included, Bungie says. If you buy Marathon afterward, you keep the items and progression you unlocked.
- Crew Up event: runs from December 8 at 12 PM PT (3 PM ET) to December 22 at 10 AM PT (1 PM ET). Redeem the code DMA-T7Y-XJL on Bungie’s code redemption page once Symbiosis is live, and its challenges appear in a new Events section of the in-game Codex. They cannot be done solo: you need at least one crewmate who has also redeemed the code, and the rewards are cosmetics.
Frequently Asked Questions
Can you play Marathon’s Expedition solo? Yes. Bungie says you can roll out solo, as a duo, or with a full trio.
Is there PvP in Expedition? No. Expedition is fully PvE, and the other Runner crews in your zone work with you.
Do you keep your loot from Expedition? Not the gear. Flash Boosts and gear found during the mode are sold when your Run Series ends, but your credits and XP carry over to the rest of Marathon.
Can you join a friend who is already in a Run Series? Yes. You pick up at the highest run in their chain, but you only have access to your faction loadouts.
Do you need to own Marathon to play Expedition? Not from December 8 to 15, when Open Play Week lets anyone play the full game. After that week, you need to own Marathon.
Can you complete Priority Contracts in Expedition? Yes. Bungie confirms Priority Contracts can be completed while in Expedition.
Is Expedition a limited-time mode? No. Bungie calls it a permanent cooperative PvE mode, and Phase 2 details are due in March.