Gensou Rougoku no Kaleidoscope

Gensō Rōgoku no Kaleidoscope (幻想牢獄のカレイドスコープ), officially abbreviated as Gerokasu (ゲロカス), is a Japanese horror visual novel written by Ryukishi07 and developed by Entergram. The story revolves around four high schoolers—Fuuka Gojou, Karin Tamaru, Mina Yuasa, and Doremi Hanabusa—who are kidnapped and forced to take part in a death game. The game was originally planned to be released on November 28, 2019, however it was indefinitely postponed due to production issues. It was eventually released a year later on December 17, 2020.

Development
Gerokasu was first announced as a project titled Sangeki Sandbox (惨劇サンドボックス) in March 2018. Entergram officially announced the game on August 8, 2019, the same day that the official website opened. The game has been described by Entergram as a "girls mental suspense" game. Former Key artist Itaru Hinoue is the game's artist and character designer. Super deformed art was drawn by Hisashi Senomoto. The scenario was written by Ryukishi07, who came up with the concept for the game after drinking several cups of sake. Hinoue and Ryukishi07 both worked together on Key's 2011 visual novel Rewrite. The music of the game was composed by HiguUmiSound of Higurashi and Umineko fame.

The limited edition releases came bundled with a setting guidebook, a drama CD, the Cards of Fate set, and an acrylic art panel featuring Fūka and Kū-chan. The setting guidebook, titled Official Setting Material Collection "Phantasm Object" (公式設定資料集「Phantasm Object」), contained character designs, commentary from the cast and staff, and a drama CD script. The drama CD, titled Voice Drama CD "Locked Room Desk Quiz Tournament" (ボイスドラマCD「密室デスクイズ大会」), is an original story where Fūka, Karin, Mina and Doremi are forced to compete in a quiz.