4X
eXplore, eXpand, eXploit,& eXterminate
- eXplore the map with units, revealing the territory's terrain or something significant hidden within the territory; what is revealed will affect the game now and/or later.
- eXpand the size of the owned area by claiming territories on the map; gaining or losing territories will affect the game.
- eXploit the owned territories by improving them, gaining something, and using it to increase your units and/or power; those 3 things--improve, gain, & use--can happen in any order.
- eXterminate other players from the game using units that can be lost; it does not have to be likely that a player can be eliminated from the game, just possible.
If it is impossible to eliminate a player from the game, but everything else (including combat) is just like a 4X, the game is known as a 3.5X.
The four Xes do not have to happen separately, they can be folded together and happen at the same time. However, all four Xes will happen in a 4X game.