What type of War Games do militaries play?

I was watching Feynman's lecture and Q*A session on: Can Machines Think? https://www.youtube.com/watch?v=ipRvjS7q1DI and there was a section where he brought up a type of War Game the Navy plays on ship cost, weapons, armor. It intrigued me as it sounded like a common game on a PC or even trading cards.

Anyone have examples or a book or two about them? It just sounds interesting.