Yuu Disk Vol. 2: Exterlien Custom

Exterlien Custom is, as the name suggest, a customized version of the game Exterlien. It was sold in Japanese bookstores bundled with a "mook", a japanese concept that is a hybrid of a magazine and a book.

While the scenario is different than in the original, the core gameplay is the same: You aim to rescue girls captured by monsters by fighting said monsters in turn-based RPG setting.