Co-Op Multiplayer in Cozy Builder: Setup Guide

This guide walks you through setting up co-op multiplayer in Cozy Builder on Steam, so you and a friend can build, decorate, and manage your cozy world together. You’ll learn what you need before starting, the exact steps to get a game going, common pitfalls to avoid, and how to fix issues if something doesn’t work.

What You’ll Need

• Two copies of Cozy Builder on Steam (one per player).
• A stable internet connection on both sides.
• Steam friends list – both players must be friends on Steam.
• Both players should have the game updated to the latest version.
• Optional: a microphone or voice chat app for communication.

Step-by-Step

1. Launch the game – Both players should start Cozy Builder from their Steam library. Make sure you’re both on the main menu.
2. Open the multiplayer menu – From the main menu, select “Multiplayer� or “Co-Op�. It’s usually the second option, below “New Game.�
3. Choose host or join – One player (the host) selects “Host Game� or “Create Lobby�. The other player selects “Join Game� or “Find Lobby.�
4. Set lobby options (host) – As host, you can set a lobby name, choose a password (optional), and decide whether to allow friends only or anyone. For a private game, select “Friends Only� or set a password.
5. Create the lobby – Click “Create� or “Host� to start the lobby. The game will generate a lobby ID or list it on the server browser.
6. Join via Steam friends (easiest) – The joining player should open their Steam overlay (Shift+Tab), find the host in their friends list, right-click, and select “Join Game� if the game supports it. Alternatively, in the in-game join menu, you can see your friends’ lobbies and click “Join� next to the host’s name.
7. Join via lobby code (if prompted) – If you’re not friends on Steam, the host can share the lobby code or invite link. The joining player enters that code in the “Join with Code� field and clicks “Join.�
8. Wait for the host to start – Once the joining player is in the lobby, the host can see them in the player list. The host clicks “Start Game� to load the world.
9. Select or create a world – The host chooses an existing save or creates a new world. Co-op uses the host’s world; the joining player will load into that world with their own character.
10. Confirm connection – After loading, both players should see their characters in the same area. You can now build, gather, and decorate together.

Common Mistakes

• Not being friends on Steam – If you’re not friends, the game may not show your lobby in the friends list. Make sure you’re friends before trying to join.
• Firewall blocking the connection – Sometimes Windows Firewall or antivirus software blocks the game’s network access. This causes the join to time out.
• Version mismatch – If one player has an older version of the game, they won’t see each other’s lobbies. Check for updates in Steam.
• Host not clicking “Startâ€� – The joining player may be in the lobby but the host forgets to press “Start Game,â€� so nothing happens.
• Using “Join Gameâ€� from Steam when the host is in the main menu – Steam’s “Join Gameâ€� only works if the host is already in a lobby. If the host is still on the main menu, the join may fail.

Tips

• Use a password for public lobbies – If you set your lobby to “Public,â€� anyone can join. Add a password to keep it private.
• Host on a wired connection – For a more stable game, the host should use an Ethernet cable instead of Wi-Fi.
• Communicate before starting – Decide who is building what area so you don’t overlap and waste resources.
• Save regularly – The host’s save file is the only one that matters. Make sure the host saves before quitting.
• Check the in-game voice chat – Cozy Builder has built-in voice chat; you can enable it in settings if you prefer not to use a separate app.

Troubleshooting

• Can’t see the lobby in the friends list – Go to the in-game join menu and look for “Friends’ Lobbies.â€� If it’s empty, ask the host to send an invite via Steam (right-click > Invite to Game).
• Connection times out – Check your firewall settings. Add the game to the allowed list in Windows Firewall. Also, restart both Steam and the game.
• Game crashes when joining – Verify the game files: right-click the game in Steam > Properties > Local Files > Verify Integrity of Game Files. Do this on both computers.
• Joining player appears as a ghost or can’t interact – This is often a lag issue. Have the host pause the game and wait a few seconds. If it persists, both players should restart the game and try again.
• Lobby not appearing in the server browser – Make sure the host selected “Publicâ€� or “Friends Onlyâ€� and not “Invite Only.â€� Also, the host’s NAT type might be strict; try forwarding ports (usually UDP 7777) or using a VPN.

Frequently Asked Questions

Do both players need to own the game?

Yes, each player needs their own copy of Cozy Builder on Steam. There is no split-screen or local co-op.

Can we play co-op with more than two players?

Cozy Builder supports up to four players in co-op. The host can invite up to three friends.

Does the joining player keep their progress?

No, the joining player’s progress in the host’s world is saved to the host’s save file. The joining player does not take anything back to their own single-player world.

Can we play co-op cross-platform?

No, Cozy Builder is currently only available on Steam (PC), so cross-platform is not an option.

What happens if the host quits?

The game ends for all players. The host’s save file is updated, and you can resume later by having the same host start the game again.

Can we use mods in co-op?

Mods are not officially supported in co-op. If you try to use mods, the game may not allow you to join or may cause crashes.

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