The patched game is unique in size and structure, often requiring users to "merge" the original game's two UMD discs into a single ISO file exceeding 2GB.

Installing the patch was a ritual. You needed a specific UMD dump. You needed xDelta. You needed to pray the offsets aligned. If you messed up, the game would crash on the opening movie. If you succeeded, you were rewarded with a menu screen depicting Class Zero standing in blood-soaked rain. The patch wasn't just code; it was a skeleton key to a locked room.