This work presents the simulation of dense crowds
of more than a million agents on the GPU. The freely available implementation is based on the OpenCL framework and runs primarily on the GPU without any significant participation of the CPU. The system is based on the continuum theory of flow fields. The simulated agents exhibit smooth trajectories and even at high densities intersections are prevented. Furthermore, emergent phenomena that have been observed in human crowds are simulated. The implementation is highly configurable and embedded into a GUI system, which allows easy extensibility and experimentation.