...you keep a turn-by-turn detailed record of all actions fought, all casualty numbers per battle, all units recruited and building constructed, and have an A3-sized pencil hand-drawn EB 1.0 province map on your bedroom wall with your current empire shaded in on it and updated every day. And you refuse to refer to historical units by anything other than their native-language names, even with people who only know the english versions.

...I do all that, by the way. Many's the look of utter confusion I've gotten when I talk about 'hoplitai' and 'phalangitai' and 'gaeroas' and 'principes'. Priceless.