Civilization is a board game designed by Francis Tresham, published in the United Kingdom in 1980 by Hartland Trefoil and in the United States in 1981 by Avalon Hill. The Civilization brand is now owned by Hasbro. It was out of print for many years, before it saw republication in 2018, by Gibsons Games. The game typically takes eight or more hours to play and is for two to seven players. Civilization is widely considered to be one of the most influential games in the strategy genre, cited as foundational to both the grand strategy and 4X subgenres. The game is also first in incorporating a technology tree (or "tech tree"), a common feature in subsequent board and video games, which allows players to gain certain items and abilities only after particular other items are obtained. The Civilization board depicts areas around the Mediterranean Sea. The board is divided into many regions. Each player plays a historic civilization and starts in the area where appropriate for that civilization, and attempts to grow and expand their empire over successive turns, trying to build the greatest civilization while minimizing the effects of calamities and war. The goal of Civilization is to be first to advance to the final space on a table called the Archaeological Succession Table (AST). The AST starts at 8,000 B.C. and ends at 250 B.C. The AST contains fifteen spaces, and players are advanced on the AST each turn. At several points, however, certain conditions must be met (such as, the civilization must have a certain number of cities) in order to advance. Since any given civilization is unlikely to meet the advancement criteria at every stage of the AST, games usually last more than fifteen turns. Civilization is unusual in that it does not focus on war and combat, as many games of its genre do. Instead, players are encouraged to trade and cooperate in order to advance. However, war and combat are entirely permissible, and are sometimes inevitable.