Security is a global concern, requiring efficient, randomized allocation and scheduling of limited security resources. To that end, we have used computational game theory to build decision aids for security agencies around the world. These decision aids are in use by agencies such as the US Coast Guard for protection of ports and ferry traffic, and the Federal Air Marshals Service and LAX police for protecting air traffic; our game-theoretic algorithms are also under evaluation for suppression of urban crime and for protection of wildlife and fisheries. I will overview my group's research in this growing area of security games.