The levels of difficulty have chiefly to do with the tempo of the game.

At a high enough tempo, ultimately humans will be unable to comprehend in real-time what is happening any longer, leading to panicked behavior and/or shock-and-awe numbness. At that point, the robot team wins.

Other factors for the difficulty levers include:

• At lower difficulty levels, impose standard socially-acceptable constraints on the movement of robots, helping ensure that robot motion remains comprehensible and relatively "tame". At higher difficulty levels, no social constraints are imposed, enabling robot motion in ways that may be unexpected and jarring, even frightening, to humans.

• At the very highest difficulty levels, decrease the risk-aversion factor of the robots, enabling motion planning of trajectories that have a higher risk of failure and even potential damage to equipment.

• One parameter that can be adjusted is the proportional gain (K_p) in the PD or PID control loops. By increasing K_p, we make the system more "springy"--it can overshoot its desired state (e.g., trajectory) by a larger margin, but it will reach the desired state quicker.