The automotive community has found to design and test autonomous systems, traditional CAE tools are not enough. The number of sensors and controls involved makes it very difficult to predict all the possible scenarios and system reactions to them. An approach to provide input to all the sensors and control systems is to use gaming engines. They are used “headless”, and in other cases with multiple users in the environment. In this paper we will highlight one case on how they are changing how the Army designs, tests, and sets requirements for autonomous ground systems.