We discuss live coding audio-visual worlds for large-scale virtual reality environments. We describe Alive, an instrument allowing multiple users to develop sonic and visual behaviors of agents in a virtual world, through a browserbased collaborative code interface, accessible while being immersed through spatialized audio and stereoscopic display. The interface adds terse syntax for query-based precise or stochastic selections and declarative agent manipulations, lazily-evaluated expressions for synthesis and behavior, event handling, and flexible scheduling.