恐怖昭和の常識 is a free iPhone game developed by MASK LLC. It is targeted towards the younger generation, specifically those born in the Heisei era, who have often been ridiculed and belittled by the older generation. This game provides them with an opportunity to strike back at the Showa generation.

The game revolves around the unbelievable common knowledge of the Showa era, which is now outdated and obsolete. Players are encouraged to laugh and have fun as they encounter these peculiar facts. However, it should be noted that the game also aims to bring nostalgia to the Showa generation.

The gameplay is simple and straightforward. Players are presented with a question, followed by an illustration. They must then tap on the area they believe is the correct answer. Upon answering correctly, they progress to the next question.

The game features background music and sound effects provided by Pocket Sound and Sound Effect Lab.