Warning: This article discusses sexual assault.

A graphic and disturbing new video game called Rape Day has been slammed by a rape prevention advocate, who says the idea is "outrageous".

The game is described by its creator, Desk Plant, as a "visual novel" where the protagonist can "verbally harass, kill people and rape women as you choose to progress the story".

Stills from the game, published by its creator to website DeviantArt, show depictions of violence against women, as well as rape.

Rape Day is currently being reviewed by online gaming platform Steam - which is known to have a lax approach to censorship - and if it passes the review, it will be available to purchase and play worldwide.

But New Zealand advocacy group Rape Prevention Education says the idea is "outrageous".

"To think that people under the age of 18 are able to access this is just plain wrong," executive director Debbie Tohill told Newshub.

"Making a game out of rape is never okay - it's outrageous, and it totally negates the impact that sexual violence has on its victims."

Rape Day is already visible to preview on Steam, with no age verification necessary, except an account linked to a credit card.