In Media Res is published as a ZIP archive containing HTML pages and directories. The documents have a complex structure with many hyperlinks and a full index. The organization is somewhat non-linear and difficult to use, though individual items are easy to locate.
The rules provide a variety of play options, including standard dice-based gaming (d10), a variant diceless option, and even a variant live-action option; the same gaming group and characters could switch between these options freely if they desired.
The core of the system involves character Skills, which are defined with several parameters including a Skill Level (1+) and actions have a Commitment Level. While Skills are intended to represent rather mundane capabilities, characters may also have Abilities, Gifts, and Flaws, which work like Skills but are considered separate categories in the game. Combat is run as a Fight Scene but has much more detail than typically found in cinematic style games. The game also includes a robust Karma system that has significant impact on routine play.