We describe the ZAROFF system, a plan-based controller for the players in a game of hide and seek. The system features visually realistic human figure animation including realistic human locomotion. We discuss the planner's interaction with a changing environment to which it has only limited perceptual access. A hierarchical planner translates the game's goals of finding hiding players into locomotion goals, assisted by a special-purpose search planner. We describe a system of parallel finite state machines for controlling the player's locomotion. Neither path-planning nor explicit instructions are used to drive locomotion; agent control and apparent complexity are the result of the interaction of a few relatively simple behaviors with a complex (and changing) environment.