The video game Shun plays near the beginning is Biohazard 6 (Resident Evil 6).
Based on the manga series "Kamisama No Iu Toori" by Muneyuki Kaneshiro and Akeji Fujimura that was published from March, 2011 to November, 2012 in Bessatsu Shonen Magazine.
Filming is begin in June, 2014 and finish October, 2014.
A controversial promotional trailer was released for this featuring several big-breasted girls in skimpy bikinis playing one of the games. Their goal was to move forward without their breasts jiggling.
Similar concept to Squid Game. Hwang Dong-Hyuk, writer and director of that Korean mini-series, originally came up with the rough structure of the show in 2010, four years before Takashi Miike released As the Gods Will," but it wasn't produced until 2021.