Osprey is a generic, universal role-playing engine (system) released under a GNU license; it is free. The game was intended to serve as a toolkit for building other games but does stand alone as a fully playable system. Characters have general characteristics (name, background), Attributes (Body, Intelligence, Will, Dexterity, Social), Skills, Advantages/Disadvantages, and (optionally) Powers. Attributes yield a dice pool, Skills implement the pool of the Attribute they are based on. Powers represent things like super-powers and are used only in some genres. Task resolution matches a dice pool roll against a Difficult Target selected by the GM, or against the dice pool roll of an opponent. In combat, an Attack Skill generally is opposed by a Defense Skill.
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