From publisher blurb: The mission of U4 is to present 4th EDITION D&D rules for use in non-fantasy settings. These include pre-modern settings, contemporary settings, and those that are far flung fantastic and futuristic. U4 is perfectly suited for any of these following campaigns: Cyberpunk Espionage Modern warfare Space opera Technofantasy Urban fantasy Wild west, with or without aliens U4 has no included setting, allowing you to explore the rules in whatever context you wish. The rules are offered in a general way, not assuming any time period. The equipment lists a wide range of various firearms. Though most are modern, there are quite a few that are retro and futuristic. Features: The new "Ladder" system which offers more adjustability with character creation. Modify your class with one of seven ladders. Eleven new classes including sniper, faceman, infiltrator, and the grappler. New armor including powered combat suits. New skills & feats. All new weapons including traditional firearms, rocket launchers, and laser rifles. Pimp your auto. Purchase vehicles and modify their features. All new opponents from fanatics to tanks. user comment The difference in version page count appears to be one of font size and formatting; the OGL version uses a MUCH larger font, but all the info appears to be the same.