This expansion, priced at $9.99 USD, drops us into the new Marinea starting world. It is a deep-sea challenge that forces players to rethink gas and liquid management from the ground up. Alongside the Reef and Abyss biomes, we are getting two new Duplicants, Kai and Minnow, who are designed to thrive in these pressurized environments. For veteran players, the real draw here is the suite of new submersible buildings and marine flora that turn the traditional 'avoid water at all costs' meta on its head.
Even if you aren't picking up the DLC immediately, a significant free update for Oxygen Not Included has rolled out for everyone. The most notable addition is the high-capacity 4k wires, which should solve a lot of mid-to-late game power grid headaches. In a classic Klei touch of humor, flatulent Duplicants will now actually produce bubbles when they pass gas underwater—a small detail that highlights the studio's commitment to their intricate simulation physics.
The launch coincides with Klei Fest 2026, a studio-wide celebration that includes a massive sale across their catalog. As a tribute to their roots, Klei has made their first-ever game, Eets, free to keep forever. For those of us running multiple colonies, the new Scramble DLC tool is a godsend, allowing you to mix and match these new aquatic features into your existing saves or custom world seeds. Whether you are building pressurized airlocks or just trying to keep your base from flooding, the depths of Marinea are waiting.
Soren