I've always enjoyed wargaming for the aspects of planning and then executing (hopefully to success). Wargames can be very simple (like Risk) to complex day long affairs like Axis and Allies Global or even longer campaigns. They also span many different levels of theatres of war, from the individual soldiers to globe spanning adventures, where losses in one theatre can set you back turns to recover.

Wargaming wasn't always a boxed experience from a store shelf. It has a long history that goes back to gunpowder age Europe as European Empires looked for different ways to train tactics (and have fun if they were aristocrats). The video below goes into exactly when did war change from a military application and became a game.