An interesting facet of Empire (at least in this day and age) was the multi-player option using a single computer. Empire features a sort of fog of war, where parts on the map you haven't visited are blacked out and enemy units are only visible assuming you have a unit in range.

So discovery of enemy cities and units is an important tactical advantage. To allow for multiplayer gaming on a single PC the game made you take turns on the hotseat. The other players would be expected to turn their backs or leave the room. At the beginning of the game this leads to people swapping in and out fairly quickly as turns last only a few seconds but later on they can last a half an hour or more.

This created an interesting social event. Typically a movie or sports event was being played in another room, while each player cycled in to have their turn. It could make for some good times as you heard cursing in the next room as players discovered what vengenance you had piled on them during their absence.

In todays multiplayer games, this particular flavour no longer quite exists, though conversely you can now play against someone in another country. And admittedly Empire games could be quite the marathon at times. Come to think of it I don't remember ever finishing a game!