Oyo Empire culture in Oyo where victory was obligatory and defeat carried the duty of committing suicide. This do-or-die policy no doubt contributed to the military aggressiveness of Oyo's generals. The Oyo Empire was the only Yoruba state to adopt cavalry; it did so because most of its territory was in the northern savannah. The origin of the cavalry is disputed; however, the Nupe, Borgu and Hausa in neighboring territories also used cavalry and may have had the same historical source. Oyo was able to purchase horses from the north and maintain them in metropolitan Oyo because of partial freedom from the
Empire: Wargame of the Century interface. Starting around 1987, "Empire: Wargame of the Century" on the Atari ST, Amiga, Commodore 64, Apple II, Macintosh and DOS was produced. In its review of the game, "Computer Gaming World" noted the improved UI, saying "the playability of an already successful system has been significantly enhanced". The game would later receive the magazine's "Game of the Year" award for 1988; in 1989 the magazine named "Empire" to its Hall of Fame for games readers rated highly over time, with a final score of 9.71 out of 12, in 1990 readers voted for the game as their "All-Time Favorite",