To run the game in Linux, change to where you unpacked openquartz in the console (for example /home/user/openquartz). Then type ./openquartz-glx

In Windows, just double-click the openquartz.exe.

In the game, first hit escape to get the menu on screen. You can navigate using the arrow keys.

Basically, now you could start a single player game by hitting "Enter" (the key on your keyboard) twice. But that's no fun yet since there is only one level with some Zombie Trees in it.
More fun is  Deathmatch against bots or real people. Go to Multiyplayer/New Game/OK and choose an episode and a map. If you set "public server" to yes, your game will be listed on the internet master server and maybe someone from the net will join.
Once you startet the match, you can add bots by hitting "end" on your keyboard and remove them by hitting "home".
Another way to add bots is using the console - that's the key just beyound escape. typing "impulse 101" will add a bot while "impulse 102" will remove one.
There is also an experimental "Monsters in Deathmatch" gametype that works with singleplayer maps (currently only start.bsp). To initiate it, type "deathmatch 7" at the console and then "map start".

Oh, by the way, did I mention that OpenQuartz can handle every deathmatch map on the web?
