This is portable C source code and documentation for compiler and runtime system of ADL, the Adventure Definition Language by Ross Cunniff. ADL is a superset of the older DDL, the Dungeon Design Language written in 1981 by Michael Urban, Chris Kostanick, Michael Stein, Bruce Adler, and Warren Usui, all of the UCLA Computer Club. Also included is the ADL source code for two sample games, "Aardvark's Museum" and "mpu" (whatever that means).