Oxygen Not Included: The Aquatic Planet Pack, from Klei Entertainment, expands the space-colony simulation into submerged survival, placing players on a flooded planetoid. The expansion introduces new underwater mechanics, liquid-focused base design, and expanded resource production specific to aquatic biomes. It adds fresh critters and farming systems alongside environmental hazards. Designed for fans of complex colony sims and existing Oxygen Not Included players, it offers new tactical layers to base management.

What kind of expansion is this?

In this expansion, you begin on Marinea, a flooded starting planetoid that shifts play toward underwater logistics and colony endurance. The pack supplies four distinct biomes: Beach, Reef, Kelp Forest, and Abyss, each with unique flora and fauna to exploit. Klei worked with community modder Aki on design, and the pack adds a named starter Duplicant, Kai, plus an unlockable Unknown Duplicant tied to the main imperative.

Is it hard to get started?

In early dives the learning curve emphasizes new survival and rescue systems. Duplicants gain Basic Swimming and Divemaster skills to extend breath-hold and reach submerged zones. When oxygen is depleted a Duplicant becomes incapacitated rather than dying; teammates can rescue, move them to oxygenated areas, and perform CPR to revive them. Those mechanics increase early micromanagement and reward careful workforce assignment and base layout.

How does the aquatic play loop change resource management?

In underwater operations the expansion retools production toward liquid handling and aquatic husbandry. Submersible Grooming, Shearing, and Milking stations enable underwater ranching; new critters include a pearl-producing giant clam and the Slogo snail, while plants such as Tower Kelp and Gum Palms add harvestables. Gum Palm latex produces Rubber for insulated conductive wires, gaskets, and protective boots. Nori and Caviar appear as higher-tier food items, and a Tidal Turbine generates electricity from liquid movement.

What keeps you coming back after the first session?

In repeated play the suite of biome-specific resources and critter-based production chains creates layered objectives that extend base optimization. Rubber and tidal power supply medium- to late-game projects, while aquatic ranching and liquid management form multi-stage goals. Community influence from Aki shows in several systems, and player reception notes the depth of aquatic mechanics, which encourages experimentation with base designs and long-term colony strategies.

Recommendation for experienced colony builders

The Aquatic Planet Pack is a demanding expansion best suited to players who already play Oxygen Not Included and enjoy long-term planning across interconnected systems. New mechanics raise the strategic ceiling and increase micromanagement, so those seeking quick sessions may find it dense. For players who enjoy methodical resource chains and environmental problem solving, the pack supplies substantial new design space and persistent goals to explore.