Gaia no Monshou ("Emblem of Gaia") is a turn-based fantasy strategy game released originally for the PC-8801 in 1987 and ported to a number of other systems, including the PC Engine. It was the first PC Engine game developed by Masaya, the label used by the NCS (Nippon Computer Systems) corporation, and a precursor to one of their most famous series: Langrisser, occasionally known as Warsong.
The player controls the army of the Land of Light, and has to repel the evil overlord Böser and his monsters. The player must build their army by spending points/cash earned in the previous battle to acquire new units before the next. In order to maximize the player's chances of victory, they have to defeat as many enemy units as possible without letting them escape while securing their own units' safety to have the most spending money for the following conflict.
The game also has a Construction Mode that allows the player to create their own scenarios with units not found in the main game. These range from sci-fi units to members of Masaya's development team.