Euphoria is a "extreme hardcore ADV" hentai video game developed and published by Clock Up. It was released on June 24 2011 on PC in Japan, and gained an English localisation release in 2015.^[1][2]

The game was notorious and infamous for it's extreme fetish and kink hentai scenes, which and reached internet meme status as a often brought up example of disturbing media from Japan. Those who defend the game, point out that if one views the game through to it's conclusion, the purpose of the game outside of just being an "edgy shock feast" becomes clearer.

The game is played like a traditional visual novel.

Players progress through scenes by progressing the dialogue and occasionally making pivotal choices.

The choices the player makes determines the story branch, with different branches leading the player to different endings.

As is typical with visual novels of this kind, there is a true ending that can be unlocked by first completing all other endings.

The game is designed to purposefully mess with the player's head, and some moments in the game attempt to trick the player with meta-fourth wall gimmicks. As the ending reveals, the general purpose of the game, from a meta point of view, is to test the player--via the protagonist--on their ability to control their sadism and retain their humanity, by purposefully tripping them up.

Takato Keisuke awakens alongside female students and a female teacher from his school, trapped in an unknown location.

A anonymous speaker informs them that in order to escape they need to play a "game": Keisuke, the "keyholder", must use various "keys" on his fellow captives, "the keyholes", to unlock the doors that stand between them and their freedom.

Keisuke realizes that this means he will need to effectively rape and torture his fellow captives. One of the captives refuses to play the game, and is consequently strapped to an electric chair, before being subjected to a brutal, and inhumane "game over" in front of the others. The truth becomes clear: you play the game, or you die an agonizing death. This awakens something within Keisuke, who has all his life suppressed a severe form of sexual sadism disorder, that gives him the desire to perform sadistic acts of rape and torture on even his best friend. Confident that he would never be in a position in life in which it would have a chance to get the upper hand over his kindness and responsibility, he has until now learned to all but ignore it. Now placed into his current circumstances, Keisuke's ability to restrain his sadistic desires is being put to the ultimate test. But to what end, and by whom, for what reason?