4X

4X refers to a genre of strategy game, usually a computer game, with four primary goals: eXplore, eXpand, eXploit and eXterminate. A 4x game can be turn-based or real-time. The best known example of this genre is Sid Meier's Civilization series.

The term "4X" was first used by Alan Emrich in the September 1993 issue of Computer Gaming World, in the review of Master of Orion. Incidentally, Emrich was later involved in the design of Master of Orion 3.^[1][2] "4X" is now used quite frequently in articles about games which follow a similar pattern.^{[3][4][5][6][7][8][9][10][11][12]}

"4X" is an abbreviation for "eXplore, eXpand, eXploit, eXterminate":^[2]

• Explore means the player must move units in the playing area to reveal the map. Some games begin with the map partially revealed (for example, Master of Orion begins with stars revealed, but planets hidden) while other games begin with no initial knowledge of the map (as in the Civilization games).

• Expand means players increase the territory under their control, usually by creating new settlements. Some 4X games also allow players to extend the political influence of existing settlements (Civilization III and later versions; Galactic Civilizations).

• Exploit means players gather and use resources in areas they control, and improve the efficiency of that usage.

• Exterminate means attacking and eliminating rival players, pushing back their territorial expansion and hindering their ability to exploit resources within that territory. Beyond the cost to the rival, there is often an additional tangible benefit to the attacker, such as acquired territory, loot, and resources.

These four phases overlap quite a lot in most 4X games, and some are designed so that exploration and expansion continue until quite late in the game, for example in Master of Orion and the Space Empires series one has to do quite a lot of research in order to colonize every type of planet.

When Emrich first used the term "4X" in 1993 the vast majority of strategy games were turn-based - Dune II, the first real-time strategy game to achieve major success, was released in 1992.^[13] Since then, the term "4X" has been applied mainly to turn-based strategy games.

But many real-time strategy games also have a similar "explore, expand, exploit, exterminate" cycle (e.g. Age of Empires series, StarCraft); the real-time strategy game Starships Unlimited has been described as a 4X game;^[4][14] and Sins of a Solar Empire is advertized as a "RT4X" (real-time 4X) game.^[15]

On the other hand not all turn-based strategy games are 4X games. Chess is an obvious example, among other reasons because the board is completely visible from the start and the size of one's forces generally diminishes as pieces are captured / exchanged. The Heroes of Might and Magic series is a borderline case - players have to "explore, expand, exploit and exterminate", but: there is no real distinction between colonization and invasion; most of the economic management is really more like raiding; research is mainly a matter of buying higher-level spell-books; and most battles are decided by vast numbers of basic units.

Some players argue that "4X" games are distinguished by placing a much greater emphasis on managing an economy and researching new technologies.^[16] But some real-time games such as Age of Empires and Empire Earth simulate the growth of an empire over thousands of years and offer more technologies (both military and economic) to research than most of the games widely recognized as "4X".

Moby Games adds a criterion that there must be victory conditions other than total conquest, in order to exclude games such as Age of Empires, WarCraft, Command & Conquer and Heroes of Might and Magic from the 4X genre.^[10] Unfortunately this attempt to clarify the definition fails, because Age of Empires does offer other victory conditions.

So any attempt to define "4X" is tentative and subject to the approval of players of the relevant games. A game is most likely to be widely accepted as "4X" if it has all of the following features in addition to the classic definition:

• it is turn-based.
• it requires significant attention to economic management and research.
• the results of battles are influenced more by the technological level of the units than by battlefield tactics or weight of numbers.

Most games which are widely recognized as 4X games have most of the features described below. But they are not included in any definition because: few 4X games offer all of them; some non-4X games also offer some of them.

4X games necessarily involve building an empire. The game setting for building such an empire is usually an Earth or an Earth-like planet, a fantasy realm, or in space.

4X games usually last longer than other strategy games, possibly taking days for a single player game while multiplayer matches are sometimes known to span weeks. This is part of the intended design. For example, one Master of Orion II strategy guide makes it clear that in a large galaxy with a low-tech start one does not expect serious warfare before about turn 110.^[17]

Many 4X games are assembled as multiple layers of gameplay, tied together to form a complex system^[18]. In this sense, each layer of gameplay becomes intricate enough to resemble a minigame of its own. For example, many 4X games have a separate screen for each settlement, and many have a special screen display for battles (e.g. Master of Magic, Space Empires). Many also have separate screens for managing research or diplomacy. This is in contrast to most RTS games, where most of the game information can comfortably fit on the map.

Major 4X games like Civilization and Master of Orion have a much larger technology tree than most other strategy games (except for multi-epoch games like Age of Empires or Empire Earth). There are 86 nodes (technologies) on the technology tree in Civilization IV, while Warcraft III distributes its upgrades across 12 leaves (buildings). And in Warcraft III one can reach the highest level of one branch of the technology tree in five steps, while the Civilization IV technology tree requires nearly 60 steps to reach the end. Master of Orion has one of the simplest technology trees, in which one can research all the way to the top of one technology area and neglect the rest (seldom advisable); Civilization has one of the most complex, since most technologies have two prerequisites and hence one cannot research any top-level technology without having researched almost all the lower-level technologies.

4X games have been criticized by strategy gamers for leading to excessive micromanagement, especially later in the game. "A common flaw of 4X games is its ability to quickly become overwhelming from its micromanaging. (Later in the game), expect to spend a lot of time taking care of small details." ^[19] This can detract from grand strategy by overloading the player with repetitive and mechanical work.

Some 4X games attempt to mitigate the burden of micromanagement. Most commentators agree that Galactic Civilizations succeeds, but Master of Orion 3's approach has had a very mixed reception.^[20][21]

All "4X" games allow a player to win by exterminating all rival players. But many offer alternative victory conditions, either to reduce the tedium of "mopping up" or to enrich the game by offering a wider range of strategies. For example:

• Many 4X games award victory to the player in first place at the end of a time limit, or once their score reaches a certain threshold.
• The Master of Orion series lets the player leverage diplomacy to be elected supreme ruler of the galaxy.
• In Galactic Civilizations one can win by researching a supreme technology.
• The Space Empires series awards victory for keeping the galaxy at peace for a specified number of turns.
• In the Civilization series one can win by being the first to colonize another solar system. Later in the series, one can win by becoming the planet leader (via United Nations or the Apostolic Palace in Civilization IV: Beyond the Sword) or by dominating the culture in the country by means of reaching a fixed percentage of the world population and surface.

While some strategy games offer shared victory and team play, "diplomacy" usually revolves around teaming up to destroy opposing players. 4X games often allow more complex diplomatic relations between competitors who are not on the same team. These range from one-time trades to long-term treaties and alliances.

In most strategy games, the only obstacles between the player and victory are the opponents - gameplay is simplified to allow players to focus on "what matters," which is usually the military aspect of the game. In some 4X games, however, there are other constraints as well:

• Exploration might be limited by impassible terrain or operational ranges (e.g. the limitations on spaceships' range in the Master of Orion series and Space Empires series). Advanced technology is often required to explore the full map.
• Expansion might be limited by maintenance costs and economic troubles that are more complex than a simple population limit, such as logistic concerns or corruption. Players are usually forced to consolidate and strengthen their current holdings, or discover new technologies that make their economy powerful enough to support further expansion (corruption is an important constraint in the Civilization series until Civilization IV).
• Exploitation of natural and human resources might be limited by pollution, disease, unhappiness, or civil unrest. The player often lacks the tools to overcome these limitations at the start of the game, requiring more advanced industrial or cultural developments (pollution is a strong constraint in the Master of Orion series and a weaker one in the Civilization series; unhappiness and civil unrest are major constraints in the Civilization and Space Empires series).
• Extermination might be limited by war fatigue, morale or the activities of a peacefully-inclined political party, forcing players to make tradeoffs between finishing their war and keeping their people happy and productive (internal politics is important in the Civilization and Galactic Civilizations series).

Traditionally depth of gameplay takes priority over polished graphics and sound in 4X games.^[22]

Many 4X games offer options to play as one of several different races or cultures, each of which has its own advantages and disadvantages. A significant number allow the player to customize their race, thus informing the player's strategy before the game even starts.

In 2002, with the pending release of Master of Orion 3, there were claims that this would be the first "5X game". Alan Emrich announced that the fifth X would be eXperience:^[2]

Normally, these games give the player total knowledge, total control, and unlimited ability to do everything at all times within the limits of their resources. The '5th X' says that there's more to it than that. If you're leading a race that is supposed to be militaristic, and you conduct affairs in a pacifistic manner, you should suffer with unrest, revolt, or even revolution. If you're sitting at the top of your civilization, you should be reading reports sent up from underlings, not managing every single spy or battle yourself.

This "experience" of sitting at the top of your civilization exists in most 4X games. Civilization includes city revolts, while you can even be voted out of power in Galactic Civilizations. Master of Orion 3 may not have innovated a new feature so much as expanded on an existing gameplay convention.

Master of Orion 3 received mixed comments from reviewers and players - a few liked the lack of detailed hands-on control but the majority found this boring and / or frustrating.^[21]

The lineage of 4x games can be traced back to board games, which had an influence on early DOS games like Reach for the Stars in the eighties. These games were turn-based, and had some of the basic elements of 4X games.

Most fans regard Sid Meier's Civilization in 1990 as the first true 4X game, with the level of detail that has become a staple of the genre. Steve Barcia's Master of Orion from 1993 is also an early landmark in the genre, and the term "4X" was coined in a review of this game.^[2] Both had more developed technology trees and diplomatic AI.

The success of both Civilization and Master of Orion sparked a golden age for the genre by the mid to late 1990s. Each company produced their own spinoffs in 1994, with Colonization as a spinoff of Civilization, and Master of Magic as a spinoff of Master of Orion. Sequels to each followed in 1996 which took advantage of the rapidly growing processing power of PCs. With the growing popularity of the genre, other 4X games such as Ascendancy emerged.

StarCraft in 1998 signalled a huge success for real-time strategy games, with many lauding the benefits of both multiplayer and the faster paced military action. Critics argued that the more complex turn-based gameplay was no longer what players wanted. This was coupled with a rushed release of Civilization III, and what many regard as an ambitious failure for Master of Orion 3.

Garnering a significant buzz from a release only 3 years earlier, Stardock released Galactic Civilizations 2 in early 2006. This is coupled with the release of Civilization IV at the end of 2005, garnering numerous awards from game critics. Many fans of 4X games believe (or at least hope) this signals a renewed interest in the genre.

Also, games like Imperium Galactica had been quietly combining 4X elements with loved elements of RTS. This splicing of genres has arguably inspired "RT4X" gameplay, with Ironclad Games developing Sins of a Solar Empire with a similar concept.

Popular 4X games in a science fiction setting include:

• Reach for the Stars (1983)
• Anacreon (1988)
• Empire (1990)
• Spaceward, Ho! (1990)
• VGA Planets (1992)
• Master of Orion (1993), Master of Orion II (1996), and Master of Orion III (2003)
• Space Empires I-V (1993-2006)
• Iron Seed (1994)
• Stars! (1995)
• Ascendancy (1995)
• Pax Imperia: Eminent Domain (1997)
• Warpath (1997)
• Star Wars: Rebellion (1998)
• Alpha Centauri (1999) with Alien Crossfire (1999) expansion pack
• Star Trek: Birth of the Federation (1999)
• Imperium Galactica I (1997) and Imperium Galactica II: Alliances (2000)
• Thousand Parsec (2001 onwards) (open source, under development)
• Haegemonia: Legions of Iron (2002) with Haegemonia: The Solon Heritage expansion pack
• Galactic Civilizations (2003) with Galactic Civilizations: Altarian Prophecy expansion pack
• FreeOrion (2006) (open source, under development)
• Galactic Civilizations II (2006) with Galactic Civilizations II: Dark Avatar expansion pack (2006)
• Sword of the Stars (2006) with Sword of the Stars: Born of Blood expansion pack (2007)
• Lost Empire (2007)
• Sins of a Solar Empire (2008) (Still Under Development)

Popular 4X games in a fantasy setting include:

• Master of Magic (1994)
• Lords of Magic (1998)
• Dominions II (2003)

Popular 4X games in a historical setting include:

• Civilization I-IV and Civilization Revolution with multiple expansion packs (1991-2008)
• Colonization (1994)
• Knights of Honor (computer game) (2004)
• Freeciv (2006)
• C-evo (2006)

Will Wright's biological sim Spore features a "3E" gameplay, its motto being Emerge, Evolve, Explore. It could be argued that it could be a "4E" game with the inclusion of Exterminate, as conquest is possible during part of the game.

• Turn-based strategy
• Real-time strategy
• Technology Tree
• Build order
• Micromanagement
• Rush