Loopers

Following Key's previous success with the production of two prior visual novels termed "kinetic novels"—Planetarian: The Reverie of a Little Planet (2004) and Harmonia (2016)—since their gameplay offers no choices or alternate endings, Loopers was one of three kinetic novels announced in October 2020 alongside Lunaria: Virtualized Moonchild (2021) and Stella of The End (2022). Planning for the project began with video game director Kazuma Takada and producer Tōya Okano, the latter of whom has been credited on the staff of Key's visual novels since providing scenario assistance with Air (2000). The game's motif was built around the concept of treasure hunting, specifically geocaching. During a production meeting, Okano suggested the idea of a geochache containing a human finger, adding an element of horror to the story.

In keeping with Key's main theme of making the end user cry, the concept for Loopers was solidified around "treasure hunting, horror and crying", to which Takada suggested Ryukishi07 of 07th Expansion be brought in to write the scenario. Ryukishi07 had previously worked with Key on the scenario for Rewrite (2011) and its fan disc Rewrite Harvest festa! (2012) because of his reputation as a horror writer.

Loopers premiered as the No. 11 game sold on Getchu.com, a major redistributor of visual novel and domestic anime products, during the month of its release. It later ranked as the No. 8 most sold computer game in Japan in 2021.

Fan reaction was to the English version was less positive. It was reported to be the lowest rated Key visual novel available in English by Western fans on the Visual Novel Database as of June 2023.