SeeD is a difficult rules set to summarize because of its modular design; character generation, for example, can follow one of six major methodologies: Class, Crystal, License, Job, Eidolon, or Limit Break. The method selected will depend upon the video game that is begin emulated as the basis of the table-top role-playing game. The Skill system is similarly modular, presenting three major systems: Talent, Reel, and Fortune. Inventory and outfitting will follow either: Equipment, Remodeling, or Bare. Finally, any of these various modules may be combined with any other combination to form a final basis of "pick and use" components that are selected primarily because they are the closest match to the emulated video game.
Generally, action resolution is percentile based and features a target number called the "Chance of Success". Players then roll percentiles and attempt to "roll under" the target. Depending upon which system(s) are being utilized, there are few to many modifiers that may apply.
The principle design goals of the system-of-systems are to 1) allow for the close emulation of nearly any video game roleplaying experience, and 2) present a fast-paced "video game" like playing experience.