does it have any standard definition?
UNANSWERABLE
which phase in the systems development life cycle is the most critical when building a video game These four elements of gameplay have been described as the four phases of a 4X computer game session. what is '4x'? 4X (abbreviation of "Explore, Expand, Exploit, Exterminate") are a subgenre of strategy-based computer and board games, and include both turn-based and real-time strategy titles.
wiki:20162077
4X [SEP] Introduction
4X (abbreviation of "Explore, Expand, Exploit, Exterminate") are a subgenre of strategy-based computer and board games, and include both turn-based and real-time strategy titles. The gameplay involves building an empire. Emphasis is placed upon economic and technological development, as well as a range of non-military routes to supremacy. 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.