Italian-style Devil

Commonly referred to as Diablo-san.
A RPG game that was developed and sold on Earth in 2030.
A landmark game in the hack-and-slash genre, and the best work in the series. A walloping 10 years passed from when the game was first announced to when it finally hit the market.
Despite is rather high difficulty, the game had universal appeal. The game featured simple gameplay mechanics and a deep item and character collection system. It was a game filled with that special magic where once you start leveling a character, you find yourself unable to stop; truly a devilish game. The addictiveness of this game gave birth to a great number of “home security guards.”1
Of course, Moon Cell, who has observed and surveyed all of Earth, has a copy in its system. This game shows up in a quest where Jinako orders Karna to search for it.

Translator's Notes
  1. ^ Home security guard = NEET.
Fate/EXTRA Material: Encyclopedia of Fate/EXTRA