Command line

Two ways to start the game, and they differ in one important respect.

Through the launcher. It passes the endpoints and hands the game a session, so the game never sees your password. Nothing below is required.

Directly. You are responsible for the three endpoint flags and for authentication. The defaults are all 127.0.0.1, so a binary started with no flags looks for a backend on your own machine and will not find one. Use the endpoints you were given with your access.

./ironlark-game \
  -c <core server> \
  -i <sign-in server> \
  -s <signalling websocket> \
  --become-host

Session

Flag	Default	Meaning
-b, --become-host	off	Host the session.
--connect-to <id>	none	Join the session hosted by this user id.
--map <id>	configured	Map to load, as <author>:<mod>. Host only; a joining player loads the host’s.
--gamemode <id>	configured	Which mod holds the gamemode role, as <author>:<mod>. Exactly one runs per session; any other installed gamemode stays unloaded.

With neither --become-host nor --connect-to, the game opens its own menu.

With --gamemode unset and nothing configured, the session resolves to the only installed candidate. It deliberately does not fall back to a named mod: a default spelled in the host would be the host knowing a specific piece of gameplay, and with two candidates installed there is no answer worth guessing — the session refuses to start and says which to pick.

Where things live

Flag	Default	Meaning
--config <path>	config/server.toml beside the install	Configuration file for this run.
--content <dir>	the install’s assets/	Directory holding workshop/. Two instances on one machine can each have their own.

See Configuration for what goes in the file.

Endpoints

Flag	Default
-c, --core-server-address	http://127.0.0.1:8080
-i, --idm-server-address	http://127.0.0.1:4433
-s, --signaling-server-address	ws://127.0.0.1:8000/connection/websocket

Authentication

Flag	Default
-e, --email	a local test account
-p, --password	a local test account

You sign in with your email address. It is not the name other players see: that comes from your account, and the server tells everyone what it is.

The defaults exist for local development against a seeded backend and are not an account on anything you would join.

Prefer the environment variable IRONLARK_SESSION_TOKEN, which carries a session established elsewhere. That is what the launcher sets, and why the game never handles your password: a process’s command line is readable by anyone on the machine, its environment is not.

NAT traversal

Only useful when reproducing a connectivity problem, or running your own relay. The pool is otherwise fetched for you — see Connectivity.

Flag	Default	Meaning
--ice-servers <urls>	fetched	Comma-separated stun: / turn: / turns: URLs, replacing the fetched set. When none are passed and none could be fetched, the game falls back to public STUN, which discovers a reflexive address and nothing more — there is no relay in the fallback, so a peer behind a symmetric NAT stays unreachable.
--turn-username, --turn-password	empty	Credentials for those TURN URLs. Meaningless without --ice-servers, since a fetched set carries its own.
--ice-transport-policy <policy>	all	relay refuses every candidate except a relayed one. A test tool: it makes a working direct connection fail on purpose.

Rendering

Flag	Default	Meaning
--uncapped	off	Render without vsync, for profiling. On by default the presentation is capped, so the game does not peg the GPU and starve the compositor and audio.