One island, two captains.
CoopFoundry brings two-player cooperative multiplayer to Captain of Industry. The host picks a save, invites a friend through the Steam overlay, and that's it — the client receives the island automatically and you are both building a minute later. No port to open, no session code to type, no server to rent.
Both machines run the same simulation in lockstep. You each keep your own camera and your own tools: one of you can be laying out a smelting line while the other runs mining contracts on the far side of the map. Everything either of you builds appears for both, in the same order, on the same tick.
Version 0.5.10 — Captain of Industry 0.8.7c, Windows x64.
What you get
- Steam invitation. Private lobby, overlay invite, Steam relay transport. Nothing to configure.
- Direct IP and LAN for players who prefer it, with automatic lobby discovery on the local network.
- Automatic save transfer. The host's island is sent and verified before play starts.
- Everything shared: building, demolition, conveyors and pipes, vehicles, terrain designations, research, storage and priority settings.
- Host-controlled pause and game speed, so nobody gets left behind.
- Self-healing synchronization. The two simulations are compared every single frame. On the rare occasion they drift apart, CoopFoundry notices immediately, puts both players back on the host's state, and you carry on — you just repeat whatever you had in progress.
- Reconnection, manual checkpoints, latency display, and in-game chat.
Good to know
- Two players per island. There is no dedicated server — the host's game is the reference.
- Both players need the same CoopFoundry version and the same DLC. Other gameplay mods are not supported yet.
- Every frame waits for both players, so a long-distance connection will cap how fast the simulation can run when you accelerate time. On a good link, full speed.
- As with any mod that touches saves, start on a copy of an island you would miss.
Install
Close the game, open the CoopFoundry folder inside the archive, and copy its contents into your Captain of Industry folder, next to Captain of Industry.exe. Do this on both machines, then launch and open Multiplayer · CoopFoundry from the main menu.
BepInEx 5.4.23.5 is bundled and required: the mod has to load before the main menu is built, and the in-game mod selector runs too late to offer a connection screen.
Tell me how it goes
This thread is the place for feedback, ideas and anything that looks wrong. Both are equally welcome — several of the best improvements so far came straight from play sessions, and a good suggestion is worth as much as a good bug report.
If something does misbehave, these make it fixable quickly:
- Both players' mod logs —
<game folder>\CoopCaptain\logs\, newest file from each machine. They record every command that crossed the connection with a fingerprint, so the two logs can be lined up side by side. - Both players' game logs, if the game itself was unhappy —
%APPDATA%\Captain of Industry\Logs\. - Diagnostic snapshots, if a message mentioned them —
<game folder>\CoopCaptain\sessions\diagnostics\. These usually pinpoint the cause outright. They do contain your island's full state, so share them only if you are comfortable with that. - Who was hosting, what you were doing, and the message shown in the F10 panel.
For suggestions, tell me what you were trying to do rather than how you would build it — that tends to lead somewhere better.
