Steam Command Line Parameters

When launching the game engine, there are a number of command-line options that can be used to change the engine environment.

-dev	Launches the game in developer mode. Useful debugging and console information is shown.
-console	Launches the game directly to the developer console, and does not show the 3D background map.
-sw	Starts the game in windowed mode.
-fullscreen	Starts the game in fullscreen mode.
-w <size>	Sets the screen width to <size> in pixels, i.e. -w 1024
-h <size>	Sets the screen height to <size> in pixels, i.e. -h 768
-condebug	Logs the contents of the developer console to <game directory>\console.log
+sv_lan 1	Launches the game in LAN mode. Useful to stop players from joining your game from the Internet.
+map <mapname>	Launches the game, then loads the map called <mapname>.bsp
-applaunch <AppID>	Launches the game with using the specified SteamAppID

Parameters using the "+" symbol are developer console commands that are executed after the engine is launched.

For example, some typical settings:

<code>Steam.exe -applaunch 280 -dev -console -sw +sv_lan 1 +map MyMap </code>

This would start a Half-Life 2: Deathmatch game in developer mode, activate the developer console, in windowed mode, and in LAN multiplayer mode, then load MyMap.bsp.