Created primarily for mature players. Commonly dealing with subjects not deemed appropriate for younger folks, are extremely realistic or intellectual/philosophical.
Alternate name: Adult
The first video game about Demographic: Mature was released in 1983.
Wizard Video Games has published all these games
Most notable trait over other audiences is that many things will remain unexplained or at least not handed over to you just to satisfy your curiosity, player is left in the dark about intentions of others and possibly of the protagonist as well.