maglin-jenebellah/subnautica-ii-coop-client

Deep Synergy Multiplayer Mod is a BepInEx plugin that adds cooperative multiplayer to Subnautica 2, a survival exploration game. It is built on the BepInEx modding framework and hooks into the game's Unity runtime without modifying game files, so mod updates stay compatible with new patches. The mod synchronizes what happens in the game world across players: item pickups, base construction, and creature behavior are timestamped and resolved so that players see the same base and world state instead of conflicting versions. It also adjusts difficulty as players join or leave, changing how often creatures spawn and how quickly resources and oxygen deplete based on the number of people in a session. For connecting players, the mod uses peer to peer networking, specifically NAT punch through and WebRTC, rather than a central login server. One player hosts a session, generates a code, and shares it with others to join. Inventory data is tracked and verified between peers using a hashing method, and if the host disconnects, the session can continue on another player's machine without losing progress. Setup involves installing BepInEx 6.0.x for Subnautica 2, downloading the mod, and copying its plugin files into the BepInEx plugins folder. Configuration happens through a JSON file where you set things like session name, maximum players, resource and oxygen multipliers, and whether PvP or friendly fire is enabled. The config also has an optional section for connecting OpenAI or Claude to generate in-game narration or lore text. Minimum requirements include 8 GB of RAM, a GTX 1060 or RX 580 graphics card, and 300 MB of storage for the mod plus 15 GB for the base game, running on Windows, macOS, or Linux including Steam Deck. It works over a peer to peer network connection rather than dedicated servers, and does not require an account login or admin privileges to run.