4X games are a genre of strategy video game 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 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 scales 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.
The earliest 4X games borrowed ideas from board games and 1970s text-based computer games. The first 4X games were turn-based, but real-time 4X games are also not uncommon. Many 4X 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 would later become a staple of the genre. In the new millennium, several 4X releases have become critically and commercially successful.