This happens mainly for game that changed Parent since 0.160
A few examples of missing parent icons: - Willow - Castle of Dracula - Spider - Dharma Doujou - Radikal Bikers - Come Back Toto - Star Trek - Bang Bang Busters - Brick Zone - Phelios - Raiden Fighters - G-Loc Air Battle - Mr. Kicker - Bubble Bobble II