From the introduction:
A player character (PC) in Spartan is built out of three elements: skills, aspects, and fate boxes. Skills give each PC quantitative strengths and weaknesses. Aspects tell the character's story. Fate boxes illustrate physical and mental condition, and also serve as a resource of narrative control.
The three elements are closely connected. Skills are used to create and destroy aspects not only about the PCs, but about the entire in-game world – to write an aspect is to create the effect it describes. In turn, aspects can be invoked to skew the odds on a skill roll by drawing attention to a relevant story detail. Fate boxes are the fuel that powers this back-and-forth... and for mortals, that fuel is very much exhaustible.
The third page of the document presents a character record sheet.