a number of historical periods, including World War II, the medieval era, or the Napoleonic era. Some examples of these are: Hearts of Iron IV, Europa Universalis IV, and Victoria II. Some strategy games are even based in an alternate history, by manipulating and rewriting certain historical facts. It is also common to see games based in science fiction or futuristic settings, as well as fantasy settings. Some strategy games are abstract, and do not try to represent a world with high fidelity. Although many of these may still involve combat in the sense that units can capture or destroy each other, these games sometimes offer non-combat challenges such as arranging units in specific patterns. However, the vast majority of computerized strategy games are representational, with more complex game mechanics. Single player, multiplayer, and massively multiplayer Strategy games include single-player gameplay, multiplayer gameplay, or both. Single player games will sometimes feature a campaign mode, which involves a series of matches against several artificial intelligence opponents. Finishing each match or mission will advance the game's plot, often with cut scenes, and some games will reward a completed mission with new abilities or upgrades. Hardcore strategy gamers tend to prefer multiplayer competition, where human opponents provide more challenging competition than the artificial intelligence. Artificial intelligence opponents often need hidden information or bonuses to provide a challenge to players. More recently, massively multiplayer online strategy games have appeared such as Shattered Galaxy from 2001. However, these games are relatively difficult to design and implement compared to other massively multiplayer online games, as the numerous player-controlled units create a larger volume of online data. By 2006, reviewers expressed disappointment with the titles produced thus far. Critics argued that strategy games are not conducive to massively multiplayer gameplay. A single victory cannot have much impact in a large persistent world, and this makes it hard for a player to care about a small victory, especially if they are fighting for a faction that is losing an overall war. However, more recent developers have tried to learn from past mistakes, resulting in Dreamlords from 2007, and Saga from 2008. In 2012, Supercell released Clash of Clans, a mobile strategy video game. History The origin of strategy video games is rooted in traditional tabletop strategy games like Chess, Checkers and Go, as well as board and miniature wargaming. The Sumerian Game, an early mainframe game written by