Gazebo pre-dates the DRC, as what Open Source Robotics Foundation CTO Nate Koenig calls a side-project. It was similar to the kinds of simulators that individual robotics labs whip up for their own research, to model the environment a system might have to contend with, as well as the system itself. But according to Koenig, he was approached by DARPA last year to not only provide a simulator for use in the DRC, but to turn Gazebo into a simulator fit for the entire world. "They didn't want to just pay for the simulator upfront, and then it goes away," Koenig says. "We've already developed things for the simulator that are outside the scope of the DRC. Easily modeling buildings, robot GUI [graphical user interface], all funded by DARPA. They see this simulator as a game-changer in terms of making robotics accessible to everyone."