G ames are real-time, dynamic, interactive computer simulations. As such,time plays an incredibly important role in any electronic game. There are many different kinds of time to deal with in a game engine-real time, game time, the local timeline of an animation, the actual CPU cycles spent within a particular function, and the list goes on. Every engine system might define and manipulate time differently. We must have a solid understanding of all the ways time can be used in a game. In this chapter, we’ll take a look at how real-time, dynamic simulation software works and explore the common ways in which time plays a role in such a simulation.