A game engine for which Hamaster Press has published a number of stand-alone supplements which can serve as a one-evening entertainment or an on-going role-playing shared story.
From the publisher:
WHAT IS AN ENGLE MATRIX GAME?
Engle Matrix Games are a simple game engine that allows players to simulate scenarios not easily done by other games. Whenever situations are fluid and up in the air, Matrix Games are there. Their flexibility comes from how turns are resolved. Rather than try to make up rules for every instance, players make an argument for what they want to happen next in the game. Another player sets a "to happen" roll and a dice toss later you know which actions become facts and which just didn’t happen. I know it sounds too simple (or too complicated) to work but it does. Matrix Games are a low tech way to game events that make super computers twitch.
What can you game with them? What about a murder mystery where no one knows who did it at the start of the game, that plays in 2 hours, and that never plays the same way twice. Or why not try a horror game in which the players discover a different evil plot each time and then save the world. Or maybe a literary game about a classic story that allows you to explore a universe of "what if" scenarios. Of course there are war game and political campaigns. There are even games for education, psychotherapy and planning. So Matrix Games live space between board games and role play games. They are neither fish nor fowl but boy do they taste good!