What they did
The poster, u/Dangerous-Sport-2347, asks Codex to suggest a good set of mods for whatever PC game they are playing. Codex then fetches each mod and its prerequisites, installs them, adjusts mod settings and writes small patches so the mods work together. In one session the poster had it fix a softlock in a modded Final Fantasy VII while the game was still running, instead of reloading a save from hours earlier.
How it went
The poster says modding used to cost them dozens of hours and now takes minutes, and that the live softlock fix worked. Several commenters report the same: one had Codex read a crash report and fix a recurring crash in the Lorerim Skyrim mod list, another had it disable a Unity setting that stopped a game launching while online. No one gives exact times or costs.
Worth knowing
The agent needs full access to the game folder and the machine to download and install files, so keep a backup of saves and the clean install before letting it patch anything. One commenter pointed out that this is ordinary tool use, not a special feature, and the thread gives no failure cases.