OpenTS Co-op

Tiberian Sun, rebuilt: shared-house co-op campaigns — several players, one force.

launcher co-op campaign experimentallauncher lobby

0.11.0 preview · 2026-10-19 · release notes

A fork of OpenTS, the open rebuild of the Command & Conquer: Tiberian Sun engine, with selectable campaign mission variants and a player-by-force control matrix: several players can share a force, and one player can control several.

The Warpzone launcher can stage its network games without port forwarding by tunnelling the game's UDP traffic.

You need: original Tiberian Sun + Firestorm data; Windows (or Wine)

What's new

From the project's release notes. Games and the launcher show these after every update.

v0.11.0 preview

2026-10-19 · on GitHub

Upstream OpenTS fixes from 19 October 2026, and the menu colors again in lobby-started shared campaigns. This is a preview build of commit f9fd1de.

This build merges 39 upstream OpenTS commits. They fix crashes when the computer plans defenses without a choice and when aircraft unload outside a team, saving games with infantry types that have no animation sequence, and several gameplay rules: guarding units engage each new target, Cloakable=yes works on aircraft, low-power build rates and railgun firepower bonuses take effect, superweapons from switched-off structures arrive suspended, and shift-clicking an object only changes the selection. Upstream also changed SPAWN.INI so that Color names a position in the rules' [Colors] list, as CnCNet launchers write it.

A shared campaign started from the network lobby gives its players the eight menu colors again, in seat order. Seat order, the host's first seat and the session identity are unchanged.

Shared campaigns · Two-machine LAN playtest

VS2022 Win32/x64 Debug/Release builds and CTest passed on this commit, together with Manual CI. The shared campaign has not been played on two real machines before this release; the LAN playtest checklist is that test.

A hand-written SPAWN.INI that gives Color=0 to 7 still starts, but the players get the first eight [Colors] entries instead of the menu colors. 0.11.0 does not list or load saves written by 0.10.0. All players need this exact fork build and the same target platform. Original game assets are required and are not included.

The release workflow attaches separate Win32 and x64 engine packages.

Send bug reports and requests for this fork to <https://ntfy.sh/opents-coop-feedback-496c07> (web page, ntfy app, or curl -d "your message" https://ntfy.sh/opents-coop-feedback-496c07). The channel is public, so leave out personal data.

Breaking changes

Enable Trigger leaves an enabled trigger's countdown running
Migration: To restart the countdown of a trigger that is already enabled, run Disable Trigger on it before Enable Trigger.

New features

Override the game window icon (by ZivDero)

Bug fixes

A failed undeploy leaves no hidden vehicle behind (by ZivDero)
Accept Verses lists shorter than five entries (by ZivDero)
Accept a CreditTicks list with fewer than two sounds (by ZivDero, CCHyper)
Alliance messages use the house's color (by ZivDero, Rampastring)
Allow ShakeScreen values below 2 (by ZivDero, CCHyper)
Cloakable=yes works on aircraft (by ZivDero, CCHyper)
Computer healers keep their allied targets (by ZivDero, JoyfulShush)
Computer houses count anti-aircraft secondary weapons (by ZivDero, Rampastring)
Computer houses keep deployed structures that cannot pack up (by ZivDero, Rampastring)
Damaged service depots use damaged art for the second repair stage (by ZivDero)
Enable Trigger leaves an enabled trigger's countdown running (by ZivDero, Rampastring)
Firepower bonuses raise railgun beam damage (by ZivDero, Rampastring)
Human houses raise no teams from AI triggers (by ZivDero, Rampastring)
Improve mission-end text (by ZivDero)
Keep Play Sound Effect (Random) within its waypoint list (by ZivDero, CCHyper)
Keep object footprints inside the map's cell storage (by ZivDero, Rampastring)
Keep the menu colors in lobby-started shared campaigns (by jarvis-jhk)
Leave scenario setup after a scenario fails to load (by ZivDero)
Low-power build coefficients take effect (by ZivDero, CCHyper)
MinDamage=0 lets armor reduce a hit to nothing (by ZivDero)
Next and Previous Object reach units in tunnels (by ZivDero, CCHyper)
Objects off the map no longer reveal the shroud (by ZivDero, JoyfulShush)
Save games with infantry types that have no sequence (by ZivDero)
Shift-clicking an object only changes the selection (by ZivDero, JoyfulShush)
Silos launch the missile of the superweapon that was fired (by ZivDero)
Stop AI defense planning crashing without a choice (by ZivDero, Rampastring)
Stop aircraft unloading crashing outside a team (by ZivDero, CCHyper)
Superweapons from switched-off structures arrive suspended (by ZivDero, Rampastring)
The pointer comes back after switching away during loading (by ZivDero)
Track titles match without regard to letter case (by ZivDero, CCHyper)
Treat a negative sight range as no sight (by ZivDero, Rampastring)
Units guarding another object engage each new target directly (by ZivDero, JoyfulShush)
Vehicle thieves are not offered allied vehicles (by ZivDero, Rampastring)
Vehicles keep their own turn rate after a carryall drops them (by ZivDero)

v0.10.0 preview

2026-10-16 · on GitHub

A two-machine LAN playtest checklist, and lobby names with spaces around them. This is a preview build of commit 7aa9720.

Two-machine LAN playtest walks two players through a shared campaign from the network lobby to the second mission: shared play, control groups, waypoints, saving, resuming after a restart and the next-mission transition. Each step says what both players should see and which files to keep when something else happens.

A shared campaign started from the network lobby now ignores spaces and tabs before and after a player's name. Such a name used to stop that player's game at launch and return it to the main menu. Two names that differ only in those spaces count as the same name, so the host cannot start until one player renames.

Runtime limits

0.10.0 does not list or load saves written by 0.9.0. All players need this exact fork build and the same target platform. Original game assets are required and are not included.

The release workflow attaches separate Win32 and x64 engine packages.

Bug fixes

Ignore spaces around lobby names in shared campaigns (by jarvis-jhk)

v0.9.0 preview

2026-10-16 · on GitHub

Shared control groups in shared campaigns, and game data from the Warpzone launcher. This is a preview build of commit 734eb80.

All players of a shared-house campaign now share its control groups. When one player selects units and presses Ctrl and a number, that number appears on the units on every player's screen, and any player who controls those forces can select the group with the number key. Assigning a number takes it only from objects of the forces the assigning player controls. A shared save keeps the groups. Each player used to keep separate groups that a load cleared. As in a campaign played alone, a control group also sets the object's recruitment group, which mission triggers read.

When the Warpzone launcher passes the folder where it found Tiberian Sun, the game reads its data from there. A folder that does not exist is ignored.

Runtime limits · Group

VS2022 Win32/x64 Debug/Release builds and CTest passed on this commit, together with Manual CI. Shared control groups were not tried in a shared campaign on real machines before this release.

0.9.0 does not list or load saves written by 0.8.0. All players need this exact fork build and the same target platform. Original game assets are required and are not included.

The release workflow attaches separate Win32 and x64 engine packages.

New features

Read the game data a launcher found (by jarvis-jhk)
Share control groups in shared campaigns (by jarvis-jhk)

Open rooms

No open rooms right now. Host one from a game or the launcher.

Mods

Categories: Maps, Mission variants. Every mod version is reviewed by a moderator before it appears.

No mods published yet.