KenshiCoop

Setup + Demo: https://www.youtube.com/watch?v=OqwVRRZEYGM

Experimental co-op multiplayer for Kenshi, built as an RE_Kenshi / KenshiLib plugin.

One player hosts their world; a friend connects (LAN, direct UDP, or Steam P2P) and plays their own squad inside it. The plugin replicates squads, NPCs, combat, inventory and equipment, direct trades between the players' squads, items dropped on the ground (both directions), base building and container contents, money, game speed, and more - and saves are coordinated: any save either player makes becomes one shared save, streamed to both machines automatically.

Status: work in progress. This is a hobby project under active development. Expect rough edges, desyncs, and crashes. Two players is the current design target.

• KenshiCoop.dll is loaded into the game by RE_Kenshi. It hooks the engine via KenshiLib and drives all game mutation on the main thread.
• Networking is ENet over UDP, with an optional Steam P2P tunnel (no port forwarding needed).
• The host is authoritative for the world; each client is authoritative for its own squad. See docs/API_REFERENCE.md for the full engine-control surface and wire protocol.

src/plugin/       The KenshiCoop plugin (net, sync/replication, engine facade, scenarios)
src/netproto/     Shared wire-protocol headers (plain C++03, compiled by everything)
src/nettest/      Standalone ENet console app (transport de-risking)
src/netsim/       Protocol simulator
src/prototest/    Wire-protocol unit tests
src/tunneltest/   Steam-tunnel socket-hook tests
scripts/          Build, deploy, session, and automated-test tooling (PowerShell)
docs/             Build guide, engine/API reference, replication pitfalls
third_party/      ENet patches, VC10 compat shim (deps are fetched, not committed)

Two players, two machines. You configure the session inside the game with an in-game panel (press F2) - you swap Steam IDs by clipboard right in the panel, so there's no config file to edit and no launcher scripts to run. (A tiny coop_config.json is only needed for LAN / direct-UDP games.)

1. Kenshi 1.0.65 (Steam).
2. RE_Kenshi 0.3.1+ installed (free Nexus mod - it loads the co-op plugin into the game).
3. Steam running and online on both machines. That's the whole network setup: the connection is Steam P2P, so there's no port forwarding, no router configuration, and no IP addresses. (A direct-UDP mode is also available for LAN / port-forwarded games.)

Grab KenshiCoop-kit.zip from the latest release and unzip it anywhere (both players). You do not need to clone this repository - but if you did, the same kit is in dist/mod-kit.

The zip contains a single KenshiCoop folder. Copy that folder into your Kenshi mods directory so you end up with <Kenshi>\mods\KenshiCoop\KenshiCoop.dll (default Steam path: C:\Program Files (x86)\Steam\steamapps\common\Kenshi\mods\). Then launch Kenshi and enable KenshiCoop in the Mods menu.

The Co-op panel works at the main menu (before you load a game) as well as in-game, so the joining player doesn't need to load anything first.

1. Press F2 to open the Co-op panel.
2. Swap Steam IDs. Each player clicks "Copy my Steam ID" and sends it to the other (Steam chat, Discord, ...). When you receive your friend's ID, copy it, then click "Paste friend's Steam ID" - the panel shows the ID it captured. This is per-session (nothing is written to disk), so re-paste it if you relaunch Kenshi.
3. Leave Transport on STEAM.
4. Host: load the save you want to play, or start a new game - pick Multiplayer (Wanderer x2) from the start list for a ready-made two-squad co-op start (see below). Then set Role: HOST and toggle Connection to ONLINE.
5. Join: straight from the main menu - no save needed - set Role: JOIN and toggle Connection to ONLINE. The host streams its world to you on connect and you load right into it. (If you already have an identical copy of the host's save on disk, it's used as-is instead of transferring.)
6. The white status line shows live state, and a status banner in the top-left corner shows it too - at the main menu as well as in-game, so a joining player can watch the transfer before the world loads. Toggle Connection to OFFLINE to leave.

LAN / direct-UDP (advanced): skip the Steam ID swap. Open <Kenshi>\mods\KenshiCoop\coop_config.json, set "transport": "udp", and put the host's address in "ip" / "port". Then in the panel set Transport: UDP and go ONLINE. The ip/port are re-read whenever you go ONLINE, so no restart is needed after an edit.

• You each control your own squad. With one squad tab per player, the host runs squad 1 and the joining player squad 2. Your friend's squad is visible and synced on your screen, but answers only to them. If your save has only one squad, move some units into a second squad tab in-game to give them a crew.
• Two-player start included. The KenshiCoop mod ships a "Multiplayer (Wanderer x2)" game start (New Game -> pick it from the list): the vanilla Wanderer start, but with two wanderers already split into separate squads, so the host gets squad 1 and the joining player squad 2 with no manual tab-splitting. The start was authored by zeroit789.
• The joining player doesn't need the host's save. The host picks the save (or starts a new game); when the join connects from the menu, the host's world is streamed over automatically. Already having an identical copy on disk just skips the transfer.
• Saving just works. Any save either player makes during a session becomes one shared save on both machines, streamed to the other side automatically. To resume next time, the host loads that save and goes online, and the join can reconnect straight from the main menu again.

• "The co-op plugin has not started" - RE_Kenshi didn't load it. Check <Kenshi>\RE_Kenshi_log.txt for KenshiCoop; reinstalling RE_Kenshi usually fixes it.
• No connection (Steam) - both Steams must be online (not offline mode), and each side must have Pasted the other player's ID (the panel shows the captured ID - confirm it matches). If "Paste friend's Steam ID" reports the clipboard wasn't a Steam ID, have your friend re-copy theirs. Look for [steam] session ... active=1 in <Kenshi>\KenshiCoop_*.log.
• "protocol mismatch" in the log - one of you has an older build; both players should re-install from the same release.

The kit's README.txt has the full setup + troubleshooting list.

The plugin must be compiled with the Visual C++ 2010 (v100) x64 toolset (a KenshiLib requirement). Full toolchain setup, gotchas, and install steps are in docs/BUILD_SETUP.md. Short version, once prerequisites are in place:

cmd //c scripts/build_plugin.cmd

Dependencies are fetched, not committed:

• KenshiLib + precompiled libs: clone KenshiLib_Examples_deps into third_party/KenshiLib_deps/
• ENet: clone lsalzman/enet into third_party/enet/enet/ and apply the patches in third_party/enet/patches/ (see third_party/enet/README.md)

scripts/ contains an automated two-client test harness: dev_cycle.ps1 rebuilds, deploys to two local installs, launches host + join, runs a named scenario, and produces a numeric PASS/FAIL verdict from the two logs. regress.ps1 runs the scenario regression suite. See docs/BUILD_SETUP.md Parts D-E for details.

• BFrizzleFoShizzle - RE_Kenshi and KenshiLib, which make plugins like this possible
• lsalzman/enet - UDP networking library
• zeroit789 - the "Multiplayer (Wanderer x2)" co-op game start (#15)
• Lo-Fi Games - Kenshi

AGPL-3.0. KenshiLib and RE_Kenshi are GPLv3; this plugin links KenshiLib under GPLv3 section 13 (GPL/AGPL combination). Not affiliated with Lo-Fi Games. Non-commercial fan project.