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4X is a genre of strategy-based video and board games in which players control an empire and "eXplore, eXpand, eXploit, and eXterminate". The term was first coined by Alan Emrich in his September 1993 preview of Master of Orion for Computer Gaming World. Since then, others have adopted the term to describe games of similar scope and design.
4X computer games are noted for their deep, complex gameplay. Emphasis is placed upon economic and technological development, as well as a range of non-military routes to supremacy. Games can take a long time to complete since the amount of micromanagement needed to sustain an empire increases as the empire grows. 4X games are sometimes criticized for becoming tedious for these reasons, and several games have attempted to address these concerns by limiting micromanagement, with varying degrees of success.
The earliest 4X games borrowed ideas from board games and 1970s text-based computer games. The first 4X computer games were turn-based, but real-time 4X games are not uncommon. Many 4X computer games were published in the mid-1990s, but were later outsold by other types of strategy games. Sid Meier's Civilization is an important example from this formative era, and popularized the level of detail that later became a staple of the genre. In the new millennium, several 4X releases have become critically and commercially successful.
In the board (and card) game domain, 4X is less of a distinct genre, in part because of the practical constraints of components and playing time. The Civilization board game that gave rise to Sid Meier's Civilization computer game, for instance, has no exploration and no extermination. Unless extermination is targeted at non-player entities, it tends to be either nearly impossible (because of play balance mechanisms, since player elimination is usually considered an undesirable feature) or certainly unachievable (because victory conditions are triggered before extermination can be completed) in board games.
The term "4X" originates from a 1993 preview of Master of Orion in Computer Gaming World by Alan Emrich, in which he rated the game "XXXX" as a pun on the XXX rating for pornography. The four Xs were an abbreviation for "EXplore, EXpand, EXploit and EXterminate". Other game commentators adopted the "4X" label to describe a game genre with specific gameplay conventions:
- Explore means players send scouts across a map to reveal surrounding territories.
- Expand means players claim new territory by creating new settlements, or sometimes by extending the influence of existing settlements.
- 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. Since in some games all territory is eventually claimed, eliminating a rival's presence may be the only way to achieve further expansion.
These four elements of gameplay have been described as the four phases of a 4X computer game session. These phases often overlap with each other and vary in length depending on the game design. For example, the Space Empires series and Galactic Civilizations II: Dark Avatar have a long expansion phase, because players must make large investments in research to explore and expand into every area.
Difficulties in definition
While many computer strategy games arguably contain a similar "explore, expand, exploit, exterminate" cycle, game journalists, developers and enthusiasts generally apply "4X" to a more specific class of games, and contrast 4X games with other strategy games such as Command & Conquer. Hence, writers have tried to show how 4X games are defined by more than just having each of the four Xs. Computer gaming sites have stated that 4X games are distinguished by their greater complexity and scale, and their intricate use of diplomacy beyond the standard "friend or foe" seen in other strategy games. Reviewers have also stated that 4X games feature a range of diplomatic options, and that they are well known for their large detailed empires and complex gameplay. In particular, 4X games offer detailed control over an empire's economy, while other computer strategy games simplify this in favor of combat-focused gameplay.
4X computer games are a subgenre of strategy games, and include both turn-based and real-time strategy titles. The gameplay involves building an empire, which takes place in a setting such as Earth, a fantasy world, or in space. Each player takes control of a different civilization or race with unique characteristics and strengths. Most 4X games represent these racial differences with a collection of economic and military bonuses.
Research and technology
4X games typically feature a technology tree, which represents a series of advancements that players can unlock to gain new units, buildings, and other capabilities. Technology trees in 4X games are typically larger than in other strategy games, featuring a larger selection of choices. Empires must generate research resources and invest them in new technology. In 4X games, the main prerequisite for researching an advanced technology is knowledge of earlier technology. This is in contrast to non-4X real-time strategy games, where technological progress is achieved by building structures that grant access to more advanced structures and units.
Research is important in 4X games because technological progress is an engine for conquest. Battles are often won by superior military technology or greater numbers, with battle tactics playing a smaller part. In contrast, military upgrades in non-4X games are sometimes small enough that technologically basic units remain important throughout the game.
Combat is an important part of 4X gameplay, because 4X games allow a player to win by exterminating all rival players, or by conquering a threshold amount of the game's universe. Some 4X games, such as Galactic Civilizations, resolve battles automatically, whenever two units from warring sides meet. This is in contrast to other 4X games, such as Master of Orion, that allow players to manage battles on a tactical battle screen. Even in 4X games with more detailed control over battles, victory is usually determined by superior numbers and technology, with battle tactics playing a smaller part. 4X games differ from other combat-focused strategy games by putting more emphasis on research and economics. Researching new technology will grant access to new combat units. Some 4X games even allow players to research different unit components. This is more typical of space 4X games, where players may assemble a ship from a variety of engines, shields, and weaponry.
4X games allow rival players to engage in diplomacy. While some strategy games may offer shared victory and team play, diplomatic relations tend to be restricted to a binary choice between an ally or enemy. 4X games often allow more complex diplomatic relations between competitors who are not on the same team. Aside from making allies and enemies, players are also able to trade resources and information with rivals.
In addition to victory through conquest, 4X games often offer peaceful victory conditions or goals that involve no extermination of rival players (although war may be still be a necessary by-product of reaching said goal). For example, a 4X game may offer victory to a player who achieves a certain score or the highest score after a certain number of turns. Many 4X games award victory to the first player to master an advanced technology, accumulate a large amount of culture, or complete an awe-inspiring achievement. Several 4X games award "diplomatic victory" to anyone who can win an election decided by their rival players, or maintain peace for a specified number of turns. Galactic Civilizations has the diplomatic victory, which involves having at alliances with at least 4 factions and no other faction be out of your alliance, there are two ways to accomplish this, ally with all factions, or ally with the minimum number of factions then destroy the rest.
4X games are known for their complex gameplay and strategic depth. Gameplay usually takes priority over elaborate graphics. Whereas other strategy games focus on combat, 4X games also offer more detailed control over diplomacy, economics, and research; creating opportunities for diverse strategies. This also challenges the player to manage several strategies simultaneously, and plan for long-term objectives.
To experience a detailed model of a large empire, 4X games are designed with a complex set of game rules. For example, the player's productivity may be limited by pollution. Players may need to balance a budget, such as managing debt, or paying down maintenance costs. 4X games often model political challenges such as civil disorder, or a senate that can oust the player's political party or force them to make peace.
Such complexity requires players to manage a larger amount of information than other strategy games. Game designers often organize empire management into different interface screens and modes, such as a separate screen for diplomacy, managing individual settlements, and managing battle tactics. Sometimes systems are intricate enough to resemble a minigame. This is in contrast to most real-time strategy games. Dune II, which arguably established the conventions for the real-time strategy genre, was fundamentally designed to be a "flat interface", with no additional screens.
Since 4X games involve managing a large, detailed empire, game sessions usually last longer than other strategy games. Game sessions may require several hours of play-time, which can be particularly problematic for multiplayer matches. For example, a small-scale game in Sins of a Solar Empire can last for over 12 hours. However, fans of the genre often expect and embrace these long game sessions; Emrich wrote that "when the various parts are properly designed, other X's seem to follow. Words like EXcite, EXperiment and EXcuses (to one's significant others)". Turn-based 4X games typically divide these sessions into hundreds of turns of gameplay.
Because of repetitive actions and long-playing times, 4X games have been criticized for excessive micromanagement. In early stages of a game this is usually not a problem, but later in a game directing an empire's numerous settlements can demand several minutes to play a single turn. This increases playing-times, which are a particular burden in multiplayer games. 4X games began to offer AI governors that automate the micromanagement of a colony's build orders, but players criticized these governors for making poor decisions. In response, developers have tried other approaches to reduce micromanagement, and some approaches have been more well received than others. Commentators generally agree that Galactic Civilizations succeeds, which GamingNexus.com attributes to the game's use of programmable governors. Sins of a Solar Empire was designed to reduce the incentives for micromanagement, and reviewers found that the game's interface made empire management more elegant. On the other hand, Master of Orion III reduced micromanagement by limiting complete player control over their empire.
Early 4X games were influenced by board games and text-based computer games from the 1970s. Cosmic Balance II, Andromeda Conquest and Reach for the Stars were published in 1983, and are now seen retrospectively as 4X games. Although Andromeda Conquest was only a simple game of empire expansion, Reach for the Stars introduced the relationship between economic growth, technological progress, and conquest.
Prior to Sid Meier, Robert T. Smith created the precursor of all 4X strategy video games: Armada 2525 (followed up by a version with enhanced graphics: Armada 2525 Deluxe). However, due to the financial problems of the publishing company Interstel Corporation, Armada 2525 never got enough marketing and attention from gamers. Future 4X space strategy games such as Master of Orion would go on to adopt the gameplay and concepts found in Armada 2525.
Armada 2526, the spiritual successor to Armada 2525 was released by Ntronium Games in 2009, 19 years after the original Armada 2525 was released in 1990.
In 1991, Sid Meier released Civilization and popularized the level of detail that has become a staple of the genre. Sid Meier's Civilization was influenced by board games such as Risk and the Avalon Hill board game also called Civilization. A notable similarity between the Civilization computer game and board game is the importance of diplomacy and technological advancement. Sid Meier's Civilization was also influenced by personal computer games such as the city management game SimCity and the wargame Empire. Civilization became widely successful and influenced many 4X games to come.
In 1991, two highly influential space games were released. VGA Planets was released for the PC, while Spaceward Ho! was released on the Macintosh. Although 4X space games were ultimately more influenced by the complexity of VGA Planets, Spaceward Ho! earned praise for its relatively simple yet challenging game design. Spaceward Ho! is notable for its similarity to the 1993 game Master of Orion, with its simple yet deep gameplay. Master of Orion also drew upon earlier 4X games such as Reach for the Stars, and is considered a classic game that set a new standard for the genre. In a preview of Master of Orion, Emrich coined the term "XXXX" to describe the emerging genre. Eventually, the "4X" label was adopted by the game industry, and is now applied to several earlier game releases.
Following the success of Civilization and Master of Orion, other developers began releasing their own 4X games. In 1994, Stardock launched its first version of the Galactic Civilizations series for OS/2, and the long-standing Space Empires series began as shareware. Ascendancy and Stars! were released in 1995, and both continued the genre's emphasis on strategic depth and empire management. Meanwhile, the Civilization and Master of Orion franchises expanded their market with versions for the Macintosh. Sid Meier's team also produced Colonization in 1994 and Civilization II in 1996, while Simtex released Master of Orion in 1993, Master of Magic in 1994 and Master of Orion II in 1996.
By the late 1990s, real-time strategy games began outselling turn-based games. As they surged in popularity, major 4X developers fell into difficulties. Sid Meier's Firaxis Games released Sid Meier's Alpha Centauri in 1999 to critical acclaim, but the game fell short of commercial expectations. Civilization III encountered development problems followed by a rushed release in 2001. Despite the excitement over Master of Orion III, its release in 2003 was met with criticism for its lack of player control, poor interface, and weak AI. Game publishers eventually became risk-averse to financing the development of 4X games.
Real Time Hybrid 4X
Eventually real-time 4X games were released, such as Imperium Galactica in 1997, Starships Unlimited in 2001, and Sword of the Stars in 2006, featuring a combination of turn-based strategy and real-time tactical combat. The blend of 4X and real-time strategy gameplay led Ironclad Games to market their 2008 release Sins of a Solar Empire as a "RT4X" game. This combination of features earned the game a mention as one of the top games from 2008, including GameSpot's award for best strategy game, and IGN's award for best PC game.
Cross-fertilization between board games and video games continued. For example, some aspects of Master of Orion III were drawn from the first edition of the board game Twilight Imperium. Even Sins of a Solar Empire was inspired by the idea of adapting the board game Buck Rogers Battle for the 25th Century into a real-time video game. Going in the opposite direction, Eagle Games made a board game adaptation of Sid Meier's Civilization in 2002, completely different from the board game that had inspired the computer game in the first place.
In 2003, Stardock released a remake of Galactic Civilizations, which was praised by reviewers who saw the game as a replacement for the Master of Orion series. In 2004 the Creative Assembly released the critically acclaimed Rome: Total War, which has spawned many sequels. Civilization IV was released at the end of 2005 and was considered the PC game of the year according to several reviewers, including GameSpot and GameSpy. It is now considered one of the greatest computer games in history, having been ranked the second-best PC game of all time by IGN. By 2008, the Civilization series had sold over eight million copies, followed the release of Civilization Revolution for game consoles soon after and Civilization V in 2010. Meanwhile, Stardock released Galactic Civilizations II, which was considered the sixth-best PC game of 2006 by GameSpy. Additionally, French developer Amplitude Studios released both Endless Space and Endless Legend. These successes have led Stardock's Brad Wardell to assert that 4X games have excellent growth potential, particularly among less hardcore players. This is in addition to the loyal base of 4X gamers who have supported free software releases such as Freeciv, FreeCol, Freeorion, Golden Age of Civilizations., and C-evo.
- Emrich, Alan (September 1993). "MicroProse's Strategic Space Opera is Rated XXXX". Computer Gaming World (Issue #110). pp. 92–93.
- Habib, J. "PyroFalkon" (2006-08-17). "Civilization IV: Warlords Guide". IGN. Archived from the original on 2012-03-12. Retrieved 2014-05-05.
- "Ironclad Games - Sins of a Solar Empire Gameplay". Ironclad Games. Archived from the original on 3 January 2008. Retrieved 2008-06-23.
Sins of a Solar Empire is a "RT4X" game, blending the epic strategy and empire management of the 4X genre with the fast-paced and tactical elements of a real-time strategy title.
- "Moby Games' 4x games Group Description". MobyGames. Archived from the original on 18 June 2008. Retrieved 2008-06-23.
- Chick, Tom (2000-10-02). "PC Retroview: Master of Orion II". IGN. Retrieved 2008-07-26.
- "Space Empires III Manual v1.10". Malfador. 1998-01-21. Archived from the original on 13 June 2008. Retrieved 2008-06-24.
- Butts, Steve (2007-02-12). "Galactic Civilizations II: Dark Avatar Review". IGN. Retrieved 2008-07-26.
- Lackey, Jeff (2007-02-28). "Review - Galactic Civilizations II: Dark Avatar". GameSpot. Archived from the original on 5 September 2008. Retrieved 2008-07-26.
- Molloy, Sean. "Sins of a Solar Empire Preview". 1UP.com. Retrieved 2008-06-23.
- "Moby Games' 4x games Group Description". MobyGames. Archived from the original on 18 June 2008. Retrieved 2008-06-23.
- Ocampo, Jason (2008-02-13). "Sins of a Solar Empire for PC Review - GameSpot". GameSpot. Archived from the original on 2013-01-10. Retrieved 2014-05-05.
- GFW Staff (2007-02-20). "Previews: Sins of a Solar Empire". 1UP.com. Retrieved 2008-07-26.
- GameDaily Staff (2008-02-05). "Sins of a Solar Empire Review (PC)". Archived from the original on 24 June 2008. Retrieved 2008-07-31.
- "Starships Unlimited: Divided Galaxies". Deaf Gamers. 2000. Archived from the original on 2012-02-05. Retrieved 2014-05-05.
- YourConscience (2006-12-16). "GalCiv2, SotS, SEV: a 4X Comparison". Tacticular Cancer. Retrieved 2008-07-26.
- Cavalli, Earnest (2008-03-17). "Review: Sins of a Solar Empire Sinfully Good". Wired. Retrieved 2008-06-23.
- VanDyk, Dave (2008-02-14). "Sins of a Solar Empire Review". GameShark. Archived from the original on 16 May 2008. Retrieved 2008-06-23.
- Accardo, Sal (2006). "GameSpy's Game of the Year 2006 - 6. Galactic Civilizations II: Dread Lords". GameSpy. Archived from the original on 8 April 2008. Retrieved 2008-03-31.
- Butts, Steve (2008-02-15). "Sins of a Solar Empire". IGN. Retrieved 2011-09-29.
- Abner, William (January 2002). "GameSpy Reviews: Starships Unlimited: Divided Galaxies". GameSpy. Archived from the original on 2007-06-29. Retrieved 2008-06-23.
- Cook, Brad (July 2006). "Find New Ways to Conquer the World in Civilization IV". Apple. Archived from the original on 25 July 2008. Retrieved 2008-06-27.
- Dobson, Jason (2008-02-01). "Joystiq interview: Ironclad talks 4X strategy with Sins of a Solar Empire". Joystiq. Archived from the original on 6 July 2008. Retrieved 2008-06-23.
- Rollings, Andrew; Adams, Ernest (2003). Andrew Rollings and Ernest Adams on Game Design. New Riders Publishing. pp. 321–345. ISBN 1-59273-001-9.
- Geryk, Bruce (2001-03-30). "A History of Real-Time Strategy Games - Dune II". GameSpot. Archived from the original on 2008-05-16. Retrieved 2008-07-26.
- Geryk, Bruce (2001-08-08). "History of Space Empire Games - The Early Years 1980-1992". GameSpot. Archived from the original on 2011-05-25. Retrieved 2014-05-05.
- Rausch, Allen "Delsyn" (2003-03-28). "GameSpy Review - Galactic Civilizations". GameSpy. Archived from the original on 2012-09-07. Retrieved 2014-05-05.
- Butts, Steve (2006-12-04). "IGN - Space Empires V Review". IGN. Retrieved 2008-07-26.
- Dulin, Ron (1998-04-15). "StarCraft for PC Review". GameSpot. Archived from the original on 2012-10-06. Retrieved 2014-05-05.
- Lackey, Jeff (2006-11-03). "Gamespot Review - Space Empires V". GameSpot. Archived from the original on 2013-01-02. Retrieved 2014-05-05.
- Brenesal, Barry (2003-04-08). "Galactic Civilizations Review". IGN. Archived from the original on 6 July 2008. Retrieved 2008-07-26.
- Geryk, Bruce (2001-08-08). "History of Space Empire Games - Master of Orion II: Battle at Antares". GameSpot. Archived from the original on 2013-01-02. Retrieved 2014-05-05.
- Lafferty, Michael (2000-08-31). "Space Empires IV Preview". Game Zone. Archived from the original on 2005-02-16. Retrieved 2008-07-26.
- Parker, Sam (2003-03-24). "Review - Master of Orion III (PC)". CNet. Retrieved 2008-07-26.
- Butts, Steve (2007-06-21). "IGN Preview - Civilization IV: Beyond the Sword Hands On". IGN. Archived from the original on 25 July 2008. Retrieved 2008-07-26.
- Booth, Neil (2008-02-19). "Sins of a Solar Empire Review". PAL Gaming Network. Archived from the original on 2009-07-03. Retrieved 2008-06-23.
- Quick, Dan (February 2002). "Master of Orion III Developer Chat". GameSpy. Archived from the original on 2008-04-21. Retrieved 2008-06-23.
- "Sins of a Solar Empire FAQ". Ironclad Games. Archived from the original on 15 May 2008. Retrieved 2008-06-23.
- Bates, Jason. "IGN: Space Empires IV Review". IGN. Retrieved 2008-04-01.
- Caspian-Kaufman, Jonatha (1996). Sid Meier's Civilization II Instruction Manual. MicroProse. pp. 67–71, 80–83.
- Barcia, Steve (1993). Master of Orion - Game manual (PDF). MicroProse. p. 62. Retrieved 2008-05-21.
- Ocampo, Jason (2006-02-07). "Gamespot Review - Galactic Civilizations II: Dread Lords Hands-On - The Spiritual Heir to Master of Orion II?". GameSpot. Archived from the original on 2006-12-22. Retrieved 2008-07-26.
- Butts, Steve (2006-07-17). "IGN Preview - Civilization IV: Warlords". IGN. Retrieved 2008-07-26.
- Butts, Steve (2003-02-04). "IGN Preview - Galactic Civilizations". IGN. Retrieved 2008-07-26.
- Rausch, Allen "Delsyn" (2003-03-28). "GameSpy Review - Galactic Civilizations". GameSpy. Archived from the original on 2012-09-05. Retrieved 2014-05-05.
- YourConscience (2007-10-07). "Review - Lost Empire". Tacticular Cancer. Retrieved 2008-07-26.
- Abner, William (2006-03-28). "Galactic Civilizations II: Dread Lords Review". GameShark. Archived from the original on 19 July 2008. Retrieved 2008-07-26.
- Villines, Joshua (2001-07-04). "Master of Orion 3 preview for PC - Game Revolution". Game Revolution. Retrieved 2008-07-26.
- Stardock (2007-01-19). "Feature: Galactic Civlizations [sic] II Alien Races, Part IV". IGN. Archived from the original on 19 July 2008. Retrieved 2008-08-15.
- Parker, Sam (2002-12-18). "Master of Orion III Hands-On Preview". GameSpot. Retrieved 2008-08-19.
- Butts, Steve (2001-06-21). "IGN - Galactic Civilizations Interview". IGN. Retrieved 2008-07-26.
- Sager, Tyler (2006-06-16). "Galactic Civilizations Review". Gaming Nexus. Retrieved 2008-07-26.
- Cork, Jeff (2008-02-04). "Game Informer: Thoughts On Sins - An Interview With Blair Fraser". Game Informer. Archived from the original on April 22, 2008. Retrieved 2008-06-23.
- "MicroProse's MASTER OF ORION III Takes Galactic Empire Building a Step Higher" (Press release). Quicksilver Software. 2000-05-11. Retrieved 2008-07-26.
- "Master of Orion 3 reviews". Metacritic. Retrieved 2008-06-20.
- Kosak, Dave "Fargo". "Rich "Zdim" Carlson of Looking Glass Studios: The History of Computer Games - Part I". GameSpy. Archived from the original on 17 June 2008. Retrieved 2008-06-18.
- "IGN Videogame Hall of Fame: Civilization". IGN. Archived from the original on 5 May 2008. Retrieved 2008-05-21.
- Edwards, Benj. "The History of Civilization". Gamasutra. Archived from the original on 31 May 2008. Retrieved 2008-05-21.
- Geryk, Bruce (2001-08-08). "GameSpot - A History of Space Empire Games: VGA Planets and Spaceward Ho!". GameSpot. Archived from the original on 2013-01-02. Retrieved 2014-05-05.
- Ocampo, Jason (2005-08-26). "The Greatest Games of All Time: Master of Orion". GameSpot. Archived from the original on 2005-11-13. Retrieved 2008-07-29.
- Walker, Mark H. (February 2002). "Strategy Gaming: Part IV -- In the Beginning". GameSpy. Archived from the original on 2008-01-08. Retrieved 2008-07-25.
- Geryk, Bruce (2001-08-08). "History of Space Empire Games - Introduction". GameSpot. Archived from the original on 2007-09-29. Retrieved 2014-05-05.
- "Galactic Civilizations Gold". StarDock. Archived from the original on 16 June 2008. Retrieved 2008-06-22.
- "MobyGames - Sid Meier's Civilization". MobyGames. Archived from the original on 16 June 2008. Retrieved 2008-06-24.
- "Master of Orion II for Mac". GameSpot. 1996. Archived from the original on 2012-07-22. Retrieved 2014-05-05.
- "MobyGames - Sid Meier Gameography". MobyGames. 2008-06-24.
- "MobyGames - List of all games of Simtex". MobyGames. Retrieved 2009-02-20.
- Walker, Mark H. (February 2002). "Strategy Gaming: Part V -- Real-Time vs. Turn-Based". GameSpy. Archived from the original on 2012-09-01. Retrieved 2014-05-05.
- Tito, Greg (2005-10-04). "Featured Article: Alpha Centauri". The Escapist. Retrieved 2008-07-28.
- Gillen, Kieron (2008-02-08). "Making Of: Soren Johnson On Civ 4". Rock Paper Shotgun. Retrieved 2008-07-26.
- Surette, Tim (2007-03-21). "Sins of a Solar Empire beta unveiled". GameSpot. Retrieved 2008-07-26.
- "GameSpot Best Games of 2008: Best Strategy Game". GameSpot. 2008-12-24. Archived from the original on 2013-01-24. Retrieved 2014-05-05.
- "GameSpy 2008 Game of the Year - PC Top 10". GameSpy. December 2008. Archived from the original on 2013-12-14. Retrieved 2014-05-05.
- "IGN PC: PC Game of the Year 2008". IGN. December 2008. Archived from the original on 2013-11-03. Retrieved 2014-05-05.
- Alexander, Leigh; Caoili, Eric; Carless, Simon; Nutt, Christian; Remo, Chris (2008-12-30). "Gamasutra's Best of 2008". GamaSutra. Retrieved 2008-01-15.
- "Master of Orion III - Designer's Diary". QuickSilver Software. 2000-12-13. Retrieved 2008-07-26.
- Fraser, Blair; Wardell, Brad (2008-04-28). "Postmortem: Ironclad/Stardock's Sins of a Solar Empire". Gamasutra. Archived from the original on 14 July 2008. Retrieved 2008-07-25.
- Bub, Andrew S. (2004-08-20). "Eagle Games' Glen Drover talks about Pirates, The Boardgame!". GameSpy. Archived from the original on 9 July 2008. Retrieved 2008-07-26.
- Gillen, Kieron (2006-03-06). "Review: Galactic Civilizations II: Dread Lords". EuroGamer. Retrieved 2008-07-28.
- 1up Staff (2003-03-26). "Reviews: Galactic Civilizations". 1up. Retrieved 2008-07-28.
- "Civ IV Recognized in "Best of 2005" Awards". 2K Games. 2005-12-20. Archived from the original on 5 September 2008. Retrieved 2008-07-26.
- Adams, Dan; Butts, Steve; Onyett, Charles (2007-03-16). "Top 25 PC Games of All Time". IGN. Retrieved 2008-07-29.
- Martin, Matt. "Grand Theft Auto series has sold 66 million units to date". gamesindustry.biz. Archived from the original on 30 March 2008. Retrieved 2008-03-23.
- Bramwell, Tom (2007-07-16). "Firaxis explains lack of Civ PSP". EuroGamer. Retrieved 2008-07-26.
- "2K Games Conquers PCs with the Release of Sid Meier's Civilization V on September 21, 2010 in North America". 2K Games. 2010-06-11. Archived from the original on 1 July 2010. Retrieved 2010-07-23.
- Wallis, Alistair (2007-07-26). "Stardock's Wardell Talks GalCiv, Indie Power". Gamasutra. Retrieved 2008-07-26.
- "Mobygames: Freeciv". MobyGames. Retrieved 2008-07-28.
- "FreeCol SourceForge project of the month". SourceForge. 2007-02-28. Archived from the original on 20 January 2009. Retrieved 2009-01-15.
- "Golden Age of Civilizations".
- Clare, Oliver (2007-01-29). "Priceless Victories". EuroGamer. Retrieved 2008-07-28.