The Version 1 of Prism used a D100 (Percentile) system for all Skill resolution mechanics and Skills were built with percentile increments in mind, an inheritance from Iron Crown Enterprises' Arms Law system. Version 1 also used a "flat" Skill system that allowed characters access to almost any Skill without prerequisites. Beginning in 1997, the author updated the game, converting the D100 system to the D20 (OGL) system for Skill resolution, and restructuring the Skill system to utilize Skill Trees. These changes were intended to form the basis of a contemplated Version 2 of Prism but this remains uncompleted. The author published this document under a moniker of "Prism Version 1.5". Because the game was designed to be modular, the new Skill System can be "plugged in" to replace the old Skill System (Chapters 5 - 8) without substantive changes to the remaining modules.