Not out of the box — but the Nitrox mod makes it co-op. Subnautica is a sci-fi survival game released in 2018, 97% positive on Steam (313,707 reviews), with 2,719 playing right now. $7.49 on Steam.
Open-source co-op; dedicated server, works well for 2–4 divers. Steam lists Subnautica as single-player, so it won't show up in Steam's own "games we both own" view as something you can play together — Ready Up counts it anyway, marked "Via mod", and you can hide mod-only games with one filter if that's not your thing.
Descend into the depths of an alien underwater world filled with wonder and peril. Craft equipment, pilot submarines and out-smart wildlife to explore lush…
Steam tags: Open World Survival Craft, Survival, Horror, Open World, Underwater, Exploration, Crafting, Base-Building
Ready Up compares two Steam libraries and shows every multiplayer game you both have — including whether Subnautica is one of them — then helps you pick tonight's game with a weighted roll or a bracket.
Compare our libraries Steam store pageTired of Subnautica? The Swap tab finds the closest unowned games of the same type that are newer or rated higher.
Ready Up is a free tool: enter two Steam usernames and it lists the multiplayer games you both own, runs a bracket to pick one, and suggests new co-op games that fit how you both play. Ratings, tags and player counts from Steam and SteamSpy; updated 2026-09-08. Powered by Steam — not affiliated with or endorsed by Valve Corporation.