User summary The Iridium System Core Reference is a free download, containing the generic RPG system that also powers several other games published by HinterWelt Enterprises. It is released under the Open Game License Version 1.0a. The download version comes with a 66-page PDF file (the complete rulebook) and seven RTF documents in which the rulebook is broken down into it's open game content components. The Core Reference includes: Character creation rules Races and classes from various HinterWelt games Weapons and equipment Magic and psionics rules A combat system