"Game Boy Wars (ゲームボーイウォーズ) is a turn-based war simulator produced by Nintendo and Intelligent Systems that was released for the Game Boy in Japan only in 1990. It is a portable follow-up to the 1988 Family Computer war simulator Famicom Wars, making it the second game in Nintendo's Wars series. A series of sequels to the original Game Boy Wars were produced by Hudson Soft.
A series of sequels to the original Game Boy Wars were later published several years after the original game was released. These sequels were developed and published by Hudson Soft instead of Nintendo and Intelligent Systems."
Source: Wikipedia, "Game_Boy_Wars", available under the CC-BY-SA License.