From the Game's Introduction:
Dreamscape is a fantasy-horror role-playing game, set in the real world and in the world of dreams.
Players take the role of characters in the game, much like characters in a book, only in this game the players make the decisions, not the author.
One of the players has a different role in the game. Her role is to help create situations and events, describe places and people that the characters meet along the way. In a way, she is an author or director but one who shares the story with the other players rather than having total control of the narrative. In this game, she is called the Dream Master (DM).
The characters in this game have two identities, with very different abilities. The first is the real-world character, who will be a normal everyday person, with few special skills and little that could be considered remarkable.
However, the character has one thing that does set him apart - the ability to enter Dreamscape, where he becomes a super-human with fantastic powers and is able to fight the demons and nightmares that invade mankind's dreams.
Much of the story develops as a discussion between the players and the DM, and as the characters do things these will either succeed as described or the DM might call for a dice roll to be made. Dice used in this game are mainly ten-sided (d10) and six-sided (d6). Dice are rolled when the outcome of an event is uncertain or when the DM (or player) feels that it would be appropriate and/or interesting.