The Sims 4 received a mature rating (18+) in Russia, which some believe is due to its portrayal of same-sex relationships.
According to a recently revised Russian content rating law, same-sex relationships are considered harmful to children.
The law was cited by the game's publisher Electronic Arts in a tweet as the reason for the age restriction.
Fans took to social media to protest about the age restrictions.
The Sims 4 is a video game published by Electronic Arts in which players must satisfy the desires and needs of a group of virtual people known as "Sims".
There are generally very few specific objectives, instead players are encouraged to experiment and explore.
If the player wishes, virtual loving relationships may be orchestrated between two Sims of the same sex, which falls foul of a Russian law intended to protect minors.
The news was tweeted by the official Russian Electronic Arts Sims account.
EA has said in a statement to video gaming website Polygon that it has no plans to alter The Sims 4.