Genre is important in all forms of art and entertainment. The world of computer games is no different. Genre provides a comfortable structure within which the player will have some frame of reference for the experiences that he/she is about to have in the game. Knowing at least some of what to expect allows the player to more quickly come to grips with the mechanics of the particular game that he/she is playing and move more smoothly through the learning curve and into pure enjoyment.

But what is it that makes a 4X game a 4X game? What are the boundaries between the 4X genre and other strategy computer games? Has the definition changed over the roughly two and a half decades of the genre’s history?

The term “4X” or “XXXX” game is ordinarily credited to Alan Emrich in his preview article for Microprose’s Master of Orion in Computer Gaming World magazine in 1993. Emrich wrote that the four “X-es” were: Explore, Expand, Exploit, and Exterminate. This description has survived intact and has come to describe a distinct sub-genre of strategy computer games. The name of this website is a portmanteau of the four “X-es” that Emrich described over 20 years ago.

At a basic level, one would expect to find the four “X-es” represented in any game in the genre in some way, shape or form.

eXplore – To be considered a 4X game, exploration of the game environment should be a key component of game play. Many games in the genre feature a detailed random map generator so that the player has a new world or universe to explore in each successive gaming session. Other games, particularly older examples of the genre, include a separate map generation utility so that players may create their own maps and share them with other members of the game’s community. Exploration can be represented in many different ways but certainly, for a game to fall squarely within the 4X genre, exploration should be an important element in the game and necessary for success.

eXpand – Expansion in the 4X genre has traditionally taken a few forms. The first, and most obvious, form is the settlement of new colonies and/or cities in addition to the player’s starting location. Expansion can also occur by building up the structures and economic power within the empire’s cities and colonies. Finally, more recent 4X games have included mechanics to expand the player’s sphere of influence within the game world both politically and economically. These forms of expansion will typically have the effect of increasing the empire’s economy and creating wealth that the player is likely to need for military upkeep and common diplomatic actions.

eXploit – A 4X game will ordinarily involve the exploitation of resources that the player discovers through exploration and controls through expansion. Exploitation can vary widely between very explicit to quite abstract. In the Civilization series, both strategic and luxury resources are visible on the strategic map and must be controlled by the player’s empire in order to enable the creation of certain military units or used to generate wealth for the empire through trade. Meanwhile, Master of Orion 2 takes a somewhat more subtle approach. Certain planet types have a greater capacity for production than other types and production-oriented buildings constructed on these high production worlds are more potent than those built on less productive planets. Either way, a 4X game usually requires the player to make use of the resources he/she has discovered in furtherance of the game’s victory conditions.

eXterminate – Combat, in some form or fashion, is virtually always a big part of a 4X game. The mechanics for combat vary quite a bit from game to game. Some games feature turn-based combat while in other games, the combat takes place in real time. There are some 4X games that actually take a very hands-off approach to combat to the extent that combat is essentially handled automatically and is decided by numerical advantage or unit statistics/design. Regardless of what form it takes, extermination of other races/civilizations is always included among whatever victory conditions a particular game may have.

But the four “Xs” themselves provide a very bare bones framework for defining the genre and differentiating it from other strategy games. What else does a 4X game need?

For one thing, a 4X game typically involves some sort of research mechanic. Regardless of the setting or time period, the player’s civilization is almost always completely ignorant in the areas of science, technology/magic, and culture when the game starts. Not to be outdone, the opponents’ civilizations are in the same cretinous boat. This odd conceit exists to give the player a clean slate with each gaming session and give the player the opportunity to shape his/her empire from the ground up. The player must choose where to focus the efforts of his/her civilization’s research ability based on the environmental conditions present in the game world, diplomatic/military situation, and enabled victory conditions.

Another element that is so common in the genre as to be practically required is diplomacy. Diplomatic interaction with other empires has been a feature of 4X games reaching back to some the earliest games in the genre. At a basic level, players are normally able to trade with AI empires, ally with them, declare war, and sue for peace. Many games go far beyond the basic and feature such things as espionage and United Nations-style voting bodies. Players are often able to build (or wreck) their relationships with individual empires over time, with AI empires typically having some capacity to remember and account for the history of interactions with the player.

Meanwhile, most 4X games provide other paths to victory beyond Exterminate, the fourth “X.” In fact, many games in the genre provide ways for the player win the game without going to war with other empires at all. Common non-military victory conditions include science/research, diplomatic, cultural, and economic. Some games even include a time based victory which calculates a score for each empire that represents that empire’s technological level, population, and military power (among other things) as a numerical score when a given turn has been reached. All of these combine to give the player a variety of paths to victory beyond the stereotypical doomstack and the inevitable steamroll over the opposition.

There is nothing, however, that says that the traditional genre conventions must remain unchanged until the sun goes nova and we are all (hopefully) playing Alpha Centauri in real life. In fact, the genre has already changed quite a bit since the days when Microprose ruled the 4X roost. There was a time, for instance, when 4X games were synonymous with turn-based strategy games. But in recent years, several developers have successfully introduced the gaming public to real time 4X games that work in ways that players could not have imagined in the early 1990s. The advent of the “indie” development scene has produced developers that are not afraid to challenge the traditional definition of the 4X genre. Some of these games bring elements from other game genres – RPG elements seem a favorite – into the 4X formula. The “grand strategy” genre, a close cousin of 4X games, is more popular than ever and includes many of the elements commonly found in the 4X genre.

All of this, however, is just one man’s opinion. What do you think is required to make a 4X game? Where (and how) would you draw the line between the 4X genre and other strategy games? How would you classify games like Crusader Kings 2 or The Last Federation – games that have a lot in common with traditional 4X games but do not easily fit into the genre? What about game common game elements like quests and random events? Are they essential for a 4X game or simply a nice diversion along the way?

Feel free to share your thoughts with the eXplorminate community in the comments below or continue the conversation on the forum!


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