The gamer's guide to the MEP Light System, the MEP Codex originally was intended to be an occasional periodical to support Mind's Eye's RPG Light system games. However, only one "issue" was ever produced. It provides supplementary material and commentary on several MEP Light games.
Cychosis: The Blitzfehler Campaign
Soul Axis: The Shade/The Gnugutl Demon
Vampires of Placidhaven
Under the Jester's Mask (reprinted from Realmwalker's Codex)