True Reality (TR) is an open source LGPL Game and Simulation Engine written entirely in Standard C++ and OpenGL. It runs on all Windows platforms and GNU/Linux. OpenSceneGraph is used as its graphics engine, along with many other open source projects for support of various features.
Take a look at the trUtil::Timer class and determine what mCustomTicks are used for, if they are used, and do we want to have them at all.