Touhou Gouyoku Ibun ~ Sunken Fossil World (Japanese: 東方剛欲異聞　～ 水没した沈愁地獄, lit.

Sunken Fossil World is the first Touhou spinoff by Twilight Frontier which is not a fighting game.

The first trial demo was released on October 6, 2019, showcasing three different boss fights present in the game.

[5] A Nintendo Switch port as well as an update featuring new playable characters and storylines was announced in May 2022.

[6] This was released on October 20, 2022, and also added English and Chinese language support to both versions of the game.