TI Multiplayer/Hosting and Joining

This page is part of the TI Multiplayer mod.

This page explains how to create and join TI Multiplayer sessions, how the lobby works, and what happens when players come and go during a campaign.

Connection types

Connection	How it works	Needs
Steam Relay (default)	Traffic runs through Steam's relay network (Steam Datagram Relay).	Terra Invicta started through Steam. No port forwarding.
Direct UDP	A direct connection to the host's IP address.	The host must allow incoming UDP on port 7777 (changeable) in the firewall/router.

The lobby room shows which one is in use: Connection: Steam Relay, Connection: Direct UDP or Connection: Direct UDP (SDR unavailable). The preferred connection is set with the Transport setting, see Settings.

A player who stops responding is dropped after 45 seconds.

Lobby browser

Click MULTIPLAYER in the main menu (above MODS). The window Terra Invicta Multiplayer - Lobbies has two tabs:

• Steam Lobbies: all open sessions worldwide, refreshed every 5 seconds. Columns Name, Players (for example 2/8) and Mode (Sandbox Campaign, Sandbox Campaign · Co-op or Skirmish). A password-protected session is marked [password]. Buttons: Create new session, Refresh, Join, Close. You only see sessions of compatible mod builds.
• Direct Connect: enter Player name, Host IP and Port (default 7777, allowed 1 - 65535), then Connect as Client or Start as Host. Direct Connect always uses Direct UDP.

Steam invites from the Steam overlay and Join Game in the Steam friends list also work.

Lobby room

The lobby room (Lobby Room - Faction Selection) shows the session name, the connection, the mode and whether this is a New session or a continued one (Last save: <date> (Turn n)).

Who	Buttons
Host	Leave, Toggle Mode (Sandbox / Skirmish), Campaign Settings, Lobby Settings, Start Game
Other players	Leave, Faction Names (after claiming a faction), Ready

Each faction row shows AI, the player's name, Offline - AI takes over or Disabled, with the buttons Claim, Release, Taken, Join (co-op), Make primary or Rejoin. The alien faction is always AI only.

• A Sandbox campaign needs at least two human players to start. Ready is only a signal to the host and is not required.
• A player in the lobby who has not claimed a faction still loads into the game, but controls nothing.

Lobby Settings (host)

• Lobby title - up to 64 characters, empty means <host>'s session.
• Password - only players who know it can join. It is never sent in clear text. A joiner has 3 attempts and 45 seconds. Players who are already connected are neither kicked nor asked for it when you set a password.
• Allow co-op (two players per faction) - Sandbox only, before the start. See Co-op.

Campaign Settings (host)

Campaign Settings opens the vanilla New Game and campaign option panels over the lobby (see Game Options). The launch button is renamed Save Campaign Settings. The X or CANCEL returns to the lobby without saving. If the panel is opened again, it still shows the unsaved changes, and a hint says so.

• Disabling a faction greys it out for everyone and releases any claim on it.
• The extra switch Extended Trading Options (default on) lets players trade ships and control points with each other, see Diplomacy and Chat.

Faction Names

Players name their own faction with Faction Names: Faction name, Adjective, Leader address and Fleet name base, with Reset to default, Cancel and Save. The host sets names in the campaign panel. Releasing a faction drops its custom names. In co-op only the faction's primary player can name it.

Starting the game

When the host clicks Start Game, every player loads the campaign. The overlay Multiplayer - Loading shows the progress: Waiting for game data from the host…, Receiving game data: x / y chunks (p%), Game data received - loading the campaign….

• If nothing happens for 5 minutes (2 minutes once data has started arriving), it shows The transfer appears to be stalled. with a Cancel button.
• If the campaign cannot be started, everyone returns to the lobby: the host sees Campaign Start Failed, the others Campaign Start Cancelled.
• The host cannot start the clock until every player has finished loading, see Time and Decisions.

Joining a running game (hot-join)

Players can join a Sandbox campaign that is already running:

1. The joiner joins the session's lobby as usual and sees Game in progress - waiting for host approval…. If the session has a password, it is asked first.
2. The host gets the window Join Request (<name> wants to join the running game. n faction(s) available.) with Accept and Decline. The request alone does not pause the game.
3. After Accept the clock stops for everyone (The clock is locked while a player is joining.), and a banner <name> is joining - game paused shows the progress. The host can Cancel it.
4. The joiner claims a free faction - or presses Rejoin on their own reserved faction - and clicks Join Game.
5. The game state is sent and loaded, then everyone sees <name> has joined the game. and the previous game speed returns.

Limits: 3 minutes to pick a faction, 5 minutes to load, and only one player can join at a time (Another player is joining right now…). While the host is in a tactical battle, the request waits (Host is in combat - waiting…). A join can be refused because the host declined, no faction is free, the mod version, game version, mods or DLC differ, or it timed out.

Leaving and rejoining

• Leaving normally (Esc → Exit): the others see <name> left the game. Their faction is now AI-controlled.
• Crash or lost connection (after 45 seconds): Connection to <name> lost. Their faction is AI-controlled until they rejoin.
• In both cases the faction is kept for its player: the lobby shows Offline - AI takes over and the chat list shows (offline). Note that the AI does not really play the faction meanwhile, see Known issues.
• To come back: start Terra Invicta again, join the session's lobby, wait for the host to accept, press Rejoin on your faction and then Join Game. If you cancel the join, your faction stays reserved.
• A faction that a player releases in the lobby of a running game goes back to the AI.
• In a co-op faction, the partner simply keeps playing.

When the host leaves (host migration)

If the host leaves or loses the connection during a Sandbox campaign, another player takes over as host:

• The others see The host left the game. A new host is taking over… or Host connection lost. Migrating…, and then Host changed to <name>.
• Every player keeps a local copy of the session, so the new host continues from its copy. If that copy is older, the campaign rolls back to it.
• After the migration the clock is paused, the lobby password is removed, and a running tactical battle is called off without result (The battle was called off - its host left the game. No result was recorded.).
• Players who are behind catch up automatically (chat: <name> is catching up - Turn i/k).
• If nobody can take over, everyone sees Host migration failed - no other player could take over. and returns to the main menu.

Host migration needs Steam lobbies and does not work with Direct Connect. If the host leaves the lobby before the game started, the others also see the "migration failed" message.

See also

• TI Multiplayer/Saves and Sessions - continuing a campaign later
• TI Multiplayer/Settings and Troubleshooting - connection problems