Once Human launches free ocean expansion 'Isle of the Forbidden' on 22

Isle of the Forbidden opens with a starting plains area where players can learn basic sailing and ship handling before venturing into four named danger zones. Each danger zone brings a distinct environmental hazard players must master: the sight-blocking Strange Mist, the sanity-draining Black Tsunami, a corrosive storm called Siu that eats at equipment and accelerates crop growth, and the explosive volcanic-like Tempest named Cheonhwa. Those hazards change how you kit out a ship and what survival skills you prioritize; the expansion also introduces a modular ship-crafting system that gives players broad freedom to design hulls, install propulsion upgrades via a progression tech tree, and fit decks with cannons, harpoons, and noncombat workstations.

Ship decks can be fitted with practical installations—automatic nets, smelters, generators, and workbenches—turning vessels into mobile fortresses and production hubs. Five distinct ghost ships drift through the ocean fog; sinking them drops rare blueprints and modules that advance crafting tiers. In addition to conventional naval combat, Isle of the Forbidden adds towering biomechanical lighthouses called the Tower of Calamity that guard each region. Players can attack these with ship weapons and personal firearms; destroying a tower unlocks higher-grade crafting stages and lets a fleet progress into deeper, more dangerous waters where the Tower of Calamity mutates into a deadlier Abyssal Lighthouse at second-tier encounters.

The expansion’s apex content centers on a gargantuan ancient being dubbed the Master of the Sea. Awakening that final encounter requires server-wide cooperation and runs on a 21-day, two-stage cadence. During Stage One, servers race to clear five regions and their Towers of Calamity as quickly as possible; rapid progress spawns random Corrupted Zones and triggers the Stage Two boss, the Owl of Ruin, earlier. Server progress toward purifying anomalies is shown in a shared progress tracker, and when the required conditions are met the Master of the Sea can be roused. The ultimate fight is a four-player cooperative raid in which teams breach the creature’s shell and strike its heart from the inside.

Isle of the Forbidden also introduces a collectible environmental infection called Duet that manipulates weather and wind via music; Duet can be captured and used as a new gameplay tool. Separately, Once Human announced it will participate as the first game in the United Nations Environment Programme–backed Green Game Jam 2027. As part of that involvement, the team will run a community environmental campaign titled “Mr. Wish’s Drifting Plague” tied to the popular infection Mister Wish through November 20. Participants receive in-game rewards including a cosmetic charity box, and selected community stories will be showcased across the game’s channels.