Marathon is getting a permanent PvE mode called Expedition, a fully cooperative roguelite you can play solo, as a duo, or as a full trio, Bungie said on November 12, 2026, in its “Dev Deep Dive: Expedition – Phase 1” post. It arrives with the Symbiosis update on December 8, as Bungie’s November 10 Steam post confirms.
Who Can Play It, and When
- Owners of Marathon: from December 8, when Symbiosis goes live.
- Everyone else: Bungie’s Open Play Week, December 8 to 15, lets anyone download and play the full game, Expedition included, without buying it. If you buy Marathon after that week, you keep the items and progression you unlocked.
- How to start: pick Expedition’s dedicated queue. It covers Perimeter, Night Marsh, Outpost, and Cryo Archive, once your Runner Level unlocks each zone.
The Details
Expedition has no rival players. Your crew works alongside other Runner crews against Tau Ceti’s horrors, and you can still complete Priority Contracts there.
- Run Series: each session is three runs of rising difficulty, in zones you choose. The third run, the Critical Incident, lets you raise the difficulty for better rewards and take on Upper Complex in Night Marsh, Pinwheel on Outpost, or a new enemy, the Tick Queen on Perimeter.
- Cash out or keep going: you can reset a series at any point to cash out your rewards, or roll a finished series into a new one to see how far you can push.
- Run Kits: each faction has its own loadouts. Your loadout is locked for the series, and faction upgrades improve the starting kit over time.
- Flash Boosts: in-run upgrades that drop from zones, tough enemies and objectives. Stacking copies of the same boost raises its rarity and potency.
- Joining late: if you join a crew mid-series, you pick up at its highest run, but with faction loadouts only.
What You Keep
Flash Boosts and the gear you pick up are sold when your Run Series ends. Your credits and XP carry on, so you can buy gear for your next Extraction run and put XP into your Cradle.
What This Means for Players
If Marathon’s PvP pressure put you off, Open Play Week is the free way back in. Our Symbiosis release date story lists everything else in the update, and our look at Bungie’s Marathon roadmap explains why PvE is coming. ARC Raiders is testing PvE too (see our PvE toggle story), and solo horde fans can try our Gears of War E-Day Horde solo guide.
When and Where
- Expedition Phase 1: December 8, 2026, with Symbiosis, on PC, PS5, and Xbox Series X|S.
- More details: Bungie’s Dev Insights Part 2 on December 1.
- Phase 2: Bungie will reveal more in March.
Marathon’s official site and Steam page have the rest.
Source: Bungie, “Dev Deep Dive: Expedition – Phase 1”, November 12, 2026.