Civilization II

As a turn-based strategy game, Civilization II models the historical development of human civilization. A player, when creating a game, may pick one of 21 historical civilizations or a custom-named civilization. The computer will intelligently control multiple rival civilizations. Only a single-player mode was available until the release of the Multiplayer Addon.

The following civilizations appear in the game: Americans, Aztecs, Babylonians, Carthaginians, Celts, Chinese, Egyptians, English, French, Germans, Greeks, Indians, Japanese, Mongols, Persians, Romans, Russians, Sioux, Spaniards, Vikings and Zulus. Barbarians are available as NPCs.

Civilization II was designed by Brian Reynolds, Douglas Caspian-Kaufman and Jeff Briggs. Following the success of Civilization, the ongoing development of a sequel was kept secret for years. The game was publicly announced when the team was in the final stage of tweaking and balancing. The game's working title was Civilization 2000.

Asked about Sid Meier's involvement in the project, Reynolds replied, "We sat down and brainstormed about it and hashed out ideas, that's about it." Emulating the recently released Doom, Reynolds implemented support for modding despite Meier's fear that customers would blame the company for poor-quality mods.

Civilization II placed second on PC Data's monthly computer game sales chart for April 1996. The game secured position 3 for the next four months, before dropping to No. 5 in September. It exited PC Data's top 10 in December, after remaining there for an additional two months.

In the United States, Civilization II was the third-best-selling computer game of the first six months of 1996, and the fifth-highest seller of the year as a whole. Worldwide, its sales surpassed 400,000 copies by August, reached 500,000 in September and topped 600,000 by November. 1 million by the end of 1996.

Several other games have been heavily inspired by Civilization II. In 2006, an N-Gage version of Civilization was released, based on Civilization II and its successor III. The open-source game Freeciv has a "ruleset" that is virtually identical to II's mechanics.

In 2011, researchers at the MIT Computer Science and Artificial Intelligence Laboratory and the University College London published the results of a machine learning system playing Civilization II, in its Freeciv implementation, which used the text from its official game manual to guide its strategy. The linguistically informed player outperformed its language-unaware counterpart, winning over 78% of games when playing against the built-in AI, a 27% absolute improvement. The same group also showed that their "non-linear Monte-Carlo search wins 80% of games against the handcrafted, built-in AI".