+### [Matrix](https://matrix.org/docs/guides/introduction)
+[![#darkplaces:matrix.org](https://img.shields.io/matrix/darkplaces:matrix.org?color=660000&label=%23darkplaces%3Amatrix.org)](https://matrix.to/#/#darkplaces:matrix.org)
+
+## Downloading and running
+
+Linux x86_64 builds are available in [GitHub CI](https://github.com/DarkPlacesEngine/darkplaces/actions?query=branch%3Amaster) artifacts.
+
+More complete builds are available in [xonotic.org](https://beta.xonotic.org/autobuild/) engine zips.
+These support Windows, Linux and macOS, and include the current libraries needed for all features.
+
+DarkPlaces supports many Quake-based games and you can select which it will run by renaming the executable so it's prefixed with the game's name, for example `rogue-sdl.exe`, or by passing a cmdline argument
+such as `-rogue`. This changes various engine behaviours and cvar defaults to suit the game.
+The supported list and related details are defined in [com_game.c](https://github.com/DarkPlacesEngine/darkplaces/blob/master/com_game.c).
+
+Mods which aren't listed there can be run with (for example) `-game quake15` in which case DP will use the same behaviours and cvar defaults as for id1 Quake.
+
+## Quake Virtual File System
+
+All of Quake's data access is through a hierarchical file system, the contents
+of the file system can be transparently merged from several sources.
+
+The "base directory" is the path to the directory holding the quake.exe and
+all game directories. This can be overridden with the "-basedir" command
+line parm to allow code debugging in a different directory. The base
+directory is only used during filesystem initialization.
+
+The "game directory" is the first tree on the search path and directory that
+all generated files (savegames, screenshots, demos, config files) will be
+saved to. This can be overridden with the "-game" command line parameter.
+If multiple "-game <gamedir>" args are passed the last one is the "primary"
+and files will be saved there, the rest are read-only.
+