subnautica-ii-coop-deepsynergy-mod

Q: How do I install subnautica-ii-coop-deepsynergy-mod?

Run npx skills add https://github.com/reason-machines/devtools-skills --skill subnautica-ii-coop-deepsynergy-mod in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/subnautica-ii-coop-deepsynergy-mod/ (personal) or .claude/skills/subnautica-ii-coop-deepsynergy-mod/ (project).

by reason-machines

Multiplayer co-op mod for Subnautica 2 using BepInEx with synchronized sessions, shared inventories, and adaptive difficulty scaling

Installs: 204
Last 24h: —
Trending rank: —
Security: Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/reason-machines/devtools-skills --skill subnautica-ii-coop-deepsynergy-mod

01
Install
Run the command in your project. The CLI asks which agents to install for.
02
Describe the task
Ask your agent for something this skill covers. It loads subnautica-ii-coop-deepsynergy-mod automatically when relevant.
03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

Subnautica II Co-op Deep Synergy Mod

Skill by ara.so — Devtools Skills collection.

What It Does

The Deep Synergy Multiplayer Mod transforms Subnautica 2 into a synchronized cooperative experience. Built on BepInEx, it provides:

Deterministic Session Synchronization (DSS): Conflict-resolved shared world state across clients
Adaptive Dynamic Scaling (ADS): Auto-adjusts creature spawns and resource respawn based on player count
Shared Inventory System: Merkle tree-based inventory tracking with peer verification
Decentralized P2P Networking: WebRTC-based multiplayer without central servers
Cross-Platform Support: Windows, Linux (Steam Deck), macOS compatibility

The mod operates as a BepInEx plugin that hooks into Subnautica 2's Unity runtime at the IL2CPP level without modifying game files.

Installation

Prerequisites

Subnautica 2 installed via Steam/GOG
BepInEx 6.0.x for Unity IL2CPP games

Steps

# 1. Install BepInEx 6.0.x for Subnautica 2
# Download from https://github.com/BepInEx/BepInEx/releases
# Extract to Subnautica 2 game directory

# 2. Download Deep Synergy Mod
# Visit: https://maglin-jenebellah.github.io

# 3. Extract mod files to BepInEx plugins directory
# <Game_Directory>/BepInEx/plugins/DeepSynergyMod/

# 4. Verify directory structure
<Subnautica2_Root>/
├── BepInEx/
│   ├── plugins/
│   │   └── DeepSynergyMod/
│   │       ├── DeepSynergy.dll
│   │       ├── SyncEngine.dll
│   │       └── NetworkLayer.dll
│   └── config/
│       └── synergy_profile.json

First Launch

# Launch Subnautica 2 through Steam/GOG
# BepInEx will initialize and load the mod
# Check BepInEx/LogOutput.log for successful plugin loading

# Expected log output:
[Info   :   BepInEx] Loading [Deep Synergy Multiplayer Mod 1.0.0]
[Info   : DeepSynergy] Session Manager initialized
[Info   : DeepSynergy] WebRTC layer ready

Configuration

Profile Configuration File

Create or edit BepInEx/config/synergy_profile.json:

{
  "session_name": "Ocean Explorers",
  "max_players": 4,
  "difficulty_scale": "adaptive",
  "resource_multiplier": 1.0,
  "oxygen_consumption": 1.0,
  "creature_spawn_divider": 1,
  "enable_pvp": false,
  "friendly_fire": false,
  "shared_blueprints": true,
  "ping_locations_shared": true,
  "time_of_day_sync": "host",
  "voice_chat_integration": "none",
  "locale": "en-US",
  "api_integration": {
    "openai": {
      "enabled": false,
      "role": "narrator",
      "api_key_env": "OPENAI_API_KEY"
    },
    "claude": {
      "enabled": false,
      "role": "lore_engine",
      "api_key_env": "CLAUDE_API_KEY"
    }
  },
  "network": {
    "port": 7777,
    "nat_punchthrough": true,
    "max_latency_ms": 250,
    "sync_interval_ms": 100
  }
}

Configuration Fields

Field	Type	Description
`session_name`	string	Display name for multiplayer session
`max_players`	int	2-8, maximum concurrent players
`difficulty_scale`	string	`"fixed"`, `"adaptive"`, `"hardcore"`
`resource_multiplier`	float	Multiplies harvestable resource nodes (0.5-3.0)
`oxygen_consumption`	float	Modifies oxygen drain rate (0.5-2.0)
`creature_spawn_divider`	int	Divides creature spawn count (1-4)
`shared_blueprints`	bool	Share blueprint unlocks across all players
`time_of_day_sync`	string	`"host"`, `"all"`, `"independent"`

Console Commands

Access via BepInEx console (F5 by default):

# Session Management
/start_server                           # Host a new session
/join_session <CODE>                    # Join existing session
/disconnect                             # Leave current session
/session_info                           # Display session details

# Synchronization
/synergy_status                         # Connection status, latency, sync progress
/force_sync                             # Manually trigger state synchronization
/inventory_verify                       # Verify inventory hash across peers

# Configuration
/synergy_scale <MULTIPLIER>             # Adjust difficulty scaling (0.5-3.0)
/resource_refresh                       # Force resource node respawn
/creature_reset                         # Reset creature AI states

# Advanced
/seed_override <SEED>                   # Set world seed for all clients
/debug_network                          # Enable network packet logging
/api_narrate "<EVENT>"                  # Trigger AI narrative generation

# Example Session Creation
> /start_server
[DeepSynergy] Starting host session...
[DeepSynergy] Session code: 9B2A-4C7D-E8F1
[DeepSynergy] Listening on port 7777
[DeepSynergy] NAT traversal: ENABLED

# Example Join
> /join_session 9B2A-4C7D-E8F1
[DeepSynergy] Connecting to session...
[DeepSynergy] Peer handshake successful
[DeepSynergy] Synchronizing world state (0%)...
[DeepSynergy] Sync complete (100%) - 2 players connected

Code Examples

Custom Mod Plugin (C# BepInEx)

Extend Deep Synergy functionality with custom plugins:

using BepInEx;
using BepInEx.IL2CPP;
using DeepSynergy.API;
using UnityEngine;

namespace CustomSynergyExtension
{
    [BepInPlugin(GUID, NAME, VERSION)]
    [BepInDependency("com.deepsynergy.core")]
    public class CustomSyncPlugin : BasePlugin
    {
        const string GUID = "com.custom.synergyplugin";
        const string NAME = "Custom Synergy Extension";
        const string VERSION = "1.0.0";

        private ISynergySessionManager sessionManager;
        private ISynergyStateSync stateSync;

        public override void Load()
        {
            // Get Deep Synergy API references
            sessionManager = DeepSynergyAPI.GetSessionManager();
            stateSync = DeepSynergyAPI.GetStateSync();

            // Subscribe to session events
            sessionManager.OnPlayerJoined += OnPlayerJoined;
            sessionManager.OnPlayerLeft += OnPlayerLeft;

            // Register custom state synchronization
            stateSync.RegisterCustomState("custom_data", SyncCustomData);

            Log.LogInfo($"{NAME} loaded successfully");
        }

        private void OnPlayerJoined(PlayerInfo player)
        {
            Log.LogInfo($"Player joined: {player.Username} (ID: {player.PeerID})");
            
            // Send welcome message to all players
            sessionManager.BroadcastMessage($"{player.Username} joined the session");
        }

        private void OnPlayerLeft(PlayerInfo player)
        {
            Log.LogInfo($"Player left: {player.Username}");
        }

        private byte[] SyncCustomData()
        {
            // Serialize custom game state data
            var customData = new CustomGameData
            {
                timestamp = Time.time,
                customValue = 42
            };
            
            return MessagePackSerializer.Serialize(customData);
        }
    }

    public struct CustomGameData
    {
        public float timestamp;
        public int customValue;
    }
}

Programmatic Session Control

using DeepSynergy.API;
using System.Threading.Tasks;

public class SessionController
{
    private ISynergySessionManager sessionManager;
    private SessionConfig config;

    public async Task<string> CreateCustomSession()
    {
        // Load configuration
        config = new SessionConfig
        {
            SessionName = "Custom Session",
            MaxPlayers = 4,
            DifficultyScale = DifficultyScaleMode.Adaptive,
            ResourceMultiplier = 1.5f,
            SharedBlueprints = true,
            NetworkConfig = new NetworkConfig
            {
                Port = 7777,
                MaxLatency = 250,
                SyncInterval = 100
            }
        };

        // Initialize session
        sessionManager = DeepSynergyAPI.GetSessionManager();
        string sessionCode = await sessionManager.CreateSessionAsync(config);

        // Register event handlers
        sessionManager.OnStateConflict += HandleStateConflict;
        sessionManager.OnSyncCompleted += OnSyncCompleted;

        return sessionCode;
    }

    private void HandleStateConflict(StateConflictEvent evt)
    {
        // Custom conflict resolution logic
        if (evt.ConflictType == ConflictType.InventoryDesync)
        {
            // Use timestamp authority
            evt.ResolveWithTimestamp();
        }
        else if (evt.ConflictType == ConflictType.BaseStructure)
        {
            // Use host authority
            evt.ResolveWithHostAuthority();
        }
    }

    private void OnSyncCompleted(SyncCompletedEvent evt)
    {
        Logger.LogInfo($"Sync complete: {evt.ItemsSynced} items, {evt.DurationMs}ms");
    }
}

Inventory Synchronization Hook

using DeepSynergy.Inventory;
using Subnautica.Items;

public class InventorySyncHook
{
    private IInventorySync inventorySync;

    public void Initialize()
    {
        inventorySync = DeepSynergyAPI.GetInventorySync();

        // Hook into game inventory events
        InventoryController.OnItemAdded += OnItemAdded;
        InventoryController.OnItemRemoved += OnItemRemoved;
    }

    private void OnItemAdded(Item item, int quantity)
    {
        // Synchronize item addition across all clients
        var syncData = new InventoryChangeData
        {
            ItemID = item.ID,
            Quantity = quantity,
            Action = InventoryAction.Add,
            Timestamp = NetworkTime.GetTimestamp()
        };

        inventorySync.BroadcastInventoryChange(syncData);
    }

    private void OnItemRemoved(Item item, int quantity)
    {
        var syncData = new InventoryChangeData
        {
            ItemID = item.ID,
            Quantity = quantity,
            Action = InventoryAction.Remove,
            Timestamp = NetworkTime.GetTimestamp()
        };

        inventorySync.BroadcastInventoryChange(syncData);
    }
}

Common Patterns

Pattern 1: Adaptive Difficulty Scaling

{
  "difficulty_scale": "adaptive",
  "resource_multiplier": 1.2,
  "creature_spawn_divider": 1,
  "oxygen_consumption": 0.9
}

With 2 players: Resources +20%, oxygen -10% drain, normal creature spawns With 4 players: Resources +40%, oxygen -20% drain, creatures ÷2

Pattern 2: Hardcore Co-op

{
  "difficulty_scale": "hardcore",
  "resource_multiplier": 0.8,
  "creature_spawn_divider": 0.5,
  "oxygen_consumption": 1.5,
  "friendly_fire": true,
  "shared_blueprints": false
}

Pattern 3: Casual Exploration

{
  "difficulty_scale": "fixed",
  "resource_multiplier": 2.0,
  "creature_spawn_divider": 2,
  "oxygen_consumption": 0.5,
  "enable_pvp": false,
  "shared_blueprints": true
}

Pattern 4: AI-Enhanced Narrative

{
  "api_integration": {
    "openai": {
      "enabled": true,
      "role": "narrator",
      "api_key_env": "OPENAI_API_KEY"
    },
    "claude": {
      "enabled": true,
      "role": "lore_engine",
      "api_key_env": "CLAUDE_API_KEY"
    }
  }
}

Console usage:

/api_narrate "discovered alien artifact in lost river"
# Returns: "The artifact pulses with an otherworldly rhythm. Thermal readings suggest it predates the last extinction event..."

Troubleshooting

Session Connection Fails

Symptom: Cannot join session with valid code

# Check network configuration
/debug_network

# Verify port forwarding (if not using NAT punchthrough)
# Ensure UDP port 7777 is open

# Check firewall rules
# Windows: Allow BepInEx/Subnautica2.exe through Windows Firewall
# Linux: sudo ufw allow 7777/udp

Solution: Enable NAT punchthrough in config:

{
  "network": {
    "nat_punchthrough": true,
    "port": 7777
  }
}

Inventory Desynchronization

Symptom: Items appear/disappear inconsistently between players

# Force inventory verification
/inventory_verify

# Check output for hash mismatch
[DeepSynergy] Inventory hash: Local=0xFA342B1E, Peer1=0xFA342B1E, Peer2=0x00000000

# Force full state sync
/force_sync

Solution: Enable stricter sync intervals:

{
  "network": {
    "sync_interval_ms": 50
  }
}

High Latency / Lag

Symptom: Actions delayed, creatures rubber-banding

# Check connection status
/synergy_status

# Output:
Connected peers: 3
Average latency: 450ms (WARNING: High latency)
Packet loss: 8%

Solution: Reduce max players or increase latency tolerance:

{
  "max_players": 2,
  "network": {
    "max_latency_ms": 500,
    "sync_interval_ms": 200
  }
}

Blueprint Unlock Not Shared

Symptom: One player unlocks blueprint, others don't receive it

Check configuration:

{
  "shared_blueprints": true
}

Force blueprint sync:

/force_sync

Mod Not Loading

Check BepInEx log (BepInEx/LogOutput.log):

[Error  :   BepInEx] Could not load [DeepSynergy.dll]
[Error  :   BepInEx] System.IO.FileNotFoundException: Missing dependency

Solution: Ensure all mod files are in correct directory:

BepInEx/plugins/DeepSynergyMod/
├── DeepSynergy.dll
├── SyncEngine.dll
├── NetworkLayer.dll
└── 0Harmony.dll (BepInEx dependency)

Creature AI Desync

Symptom: Leviathans appear in different locations for each player

# Reset creature AI states
/creature_reset

# Force synchronize all creature positions
/force_sync

Prevention: Lower creature spawn divider to reduce AI state complexity:

{
  "creature_spawn_divider": 2
}

Session Code Not Generating

Check console output:

> /start_server
[Error] Port 7777 already in use

Solution: Change port or kill conflicting process:

{
  "network": {
    "port": 7778
  }
}

Or on Linux:

sudo lsof -i :7777
kill <PID>

Environment Variables

For API integrations (optional):

# OpenAI API key for narrative generation
export OPENAI_API_KEY="sk-proj-..."

# Anthropic Claude API key for lore engine
export CLAUDE_API_KEY="sk-ant-..."

Reference in configuration:

{
  "api_integration": {
    "openai": {
      "api_key_env": "OPENAI_API_KEY"
    }
  }
}

Performance Optimization

For Low-End Systems

{
  "max_players": 2,
  "resource_multiplier": 1.0,
  "creature_spawn_divider": 2,
  "network": {
    "sync_interval_ms": 200,
    "max_latency_ms": 500
  }
}

For High-End Systems / LAN

{
  "max_players": 8,
  "network": {
    "sync_interval_ms": 50,
    "max_latency_ms": 100
  }
}

Key Files

BepInEx/config/synergy_profile.json - Main configuration
BepInEx/LogOutput.log - BepInEx and mod logs
BepInEx/plugins/DeepSynergyMod/ - Mod DLL files
Subnautica2_Data/Managed/ - Game assemblies (do not modify)

Resources

BepInEx Documentation: https://docs.bepinex.dev/
Subnautica Modding Wiki: https://subnauticamodding.github.io/
Discord Support: Available 24/7 (see project homepage)

FAQ

What does the subnautica-ii-coop-deepsynergy-mod skill do?

Multiplayer co-op mod for Subnautica 2 using BepInEx with synchronized sessions, shared inventories, and adaptive difficulty scaling

How do I install subnautica-ii-coop-deepsynergy-mod?

Run npx skills add https://github.com/reason-machines/devtools-skills --skill subnautica-ii-coop-deepsynergy-mod in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/subnautica-ii-coop-deepsynergy-mod/ (personal) or .claude/skills/subnautica-ii-coop-deepsynergy-mod/ (project).

Which AI agents can use subnautica-ii-coop-deepsynergy-mod?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is subnautica-ii-coop-deepsynergy-mod safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains subnautica-ii-coop-deepsynergy-mod?

It is published by reason-machines in reason-machines/devtools-skills. It has 204 recorded installs.

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subnautica-ii-coop-deepsynergy-mod

Install

Install

Describe the task

Review the result

SKILL.md

Subnautica II Co-op Deep Synergy Mod

What It Does

Installation

Prerequisites

Steps

First Launch

Configuration

Profile Configuration File

Configuration Fields

Console Commands

Code Examples

Custom Mod Plugin (C# BepInEx)

Programmatic Session Control

Inventory Synchronization Hook

Common Patterns

Pattern 1: Adaptive Difficulty Scaling

Pattern 2: Hardcore Co-op

Pattern 3: Casual Exploration

Pattern 4: AI-Enhanced Narrative

Troubleshooting

Session Connection Fails

Inventory Desynchronization

High Latency / Lag

Blueprint Unlock Not Shared

Mod Not Loading

Creature AI Desync

Session Code Not Generating

Environment Variables

Performance Optimization

For Low-End Systems

For High-End Systems / LAN

Key Files

Resources

FAQ

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