If you open the file assaultcube.bat (or the respective .sh file in linux) with a text editor, you can add or change command line options. Some of these settings can be set ingame as well using the menu.
-wX sets desired screen width to X, default is -w640
-hY sets desired screen height to Y, default is -h480
-t runs windowed
-zN sets the z-buffer precision to N bits. This should be at least 24 or you may experience depth problems.
-bN sets the screen to N bits per pixel
-aN sets FSAA (Full Scene AntiAliasing) to N samples, i.e. -a4 is 4xFSAA
-vN enables vsync if N is greater 0
--init executes the init script before starting the graphics and sound subsystems (recommended). By default the script config/init.cfg is used, but you can override this setting by using --init=yourfile.cfg
--mod=PATH adds the specified path to the list of directories that are searched when loading resources. Use this to add your own mods in a clean way without placing files into the main directory.
--home=PATH specifies the home directory for the user profile, AssaultCube will write custom settings and files to this directory (recommended).
-d This starts AssaultCube as a dedicatated server. The default is a non-dedicated server with only a single client in graphical mode. See the Server Section.
-uN sets the server upstream bandwidth to N bytes per second. only set this parameter if you know what you are doing, specifying a wrong value is worse than not specifying it at all.
-nS sets the server description, for people pinging the server. usually does not need to be set if you have a descriptive domain name already, but if you set it, keep it short as it may otherwise be truncated, i.e. -nBobsInstagibServer
-iIP sets the server ip to IP. this option is only useful for people running on machines with multiple network interfaces.
-mM sets the master server to use for either server (registering) and client (updating) to M. M is the base url of the master server and has to end in a / and without a http:// prefix, the default is masterserver.cubers.net/cgi-bin/AssaultCube.pl/. If you want your server to be private and not report to the masterserver, use -mlocalhost.
-pPASS sets the server password to PASS. Only clients that use the command "password PASS" will be able to connect.
-cN sets the maximum number of players that can play on this server to N (default 6). If more players try to connect they will get a "server full" message.
-xM sets the admin password.
-rC sets the maprotation file, e.g. -rconfig/maprot.cfg
-oN sets the server's message of the day.
-kN sets the score threshold. If a players score drops below it, he will be kicked automatically. (default: -5)
-sW starts the server as windows service and sets the name of the windows service that should be used. Works only for the server binary is started directly from the windows service manager.