In the context of the "CODEX" release file you mentioned, this is not a new story expansion but a technical patch. Historically, this update focused on:
: To fight back against the superior alien technology, Ty must recover powerful artifacts, specifically the Bunyip Gauntlets, which allow him to pilot massive combat mechs. TY.the.Tasmanian.Tiger.3.Update.v1.01-CODEX.rar
: Better support for controllers and keyboard mapping. In the context of the "CODEX" release file
: Fixing glitches where textures or sound effects wouldn't trigger correctly during cutscenes. Ty must recover powerful artifacts