Mature Content Description

The developers describe the content like this:

The game features sexual acts between consenting adults. The sexual content features themes such as NTR (Cheating), Swinging (Partner Swapping), and BDSM.

About This Game

Cuckoo Mask is a non-combat, narrative focused RPG that explores the dynamics of open relationships, fetish, and cheating. The game follows the story of a main character who gets bullied in a... fun and sexy way!

You just missed the last train of the day and are feeling lost, but you stumbles upon a masked party where you see a girl who looks like your girlfriend. Everyone at the party wears a mask, and the owner of the house is nowhere to be seen. You soon discover that no one you meet is inclined to treat you well, but... you soon finds yourself enjoying the mistreatment.

EXPLORATION & TIME ADVANCEMENT
Players can freely explore the house, talk to anyone, and freely examine the rooms. Time passes as the player progresses through a character's route, with dialogues changing every hour to create the feeling of a real party.

LOTS OF ART
Illustrations by myself, Hassel_Nut! I've pumped as much of my horny energy into the art as possible!

KINK & BDSM
Experience different aspects of the being dominated, teased, and humiliated!

ROSTER OF COLORFUL CHARACTERS
Secondary characters with  their own unique personalities, who also love to bully you and steal your girlfriend!

(mostly) NO SEX FOR THE PROTAGONIST?
The main character will NOT have any sexual encounter, even though other characters do. Because you're a LOSER!!!
(okay there is a bit where you can have sex but it's optional, you gotta work for it, piggy)