Abyssal Game: I Brought an Old-Version Bug

One day, the survival MMORPG Abyss Game launches simultaneously across the globe. There is no logout function, and death in-game means true death in reality. On the surface, it follows the traditional MMORPG formula—monster grinding, party dungeons, gear and skill progression, and class-based roles. But with five billion people trapped inside, society collapses; game guilds rise to replace governments and institutions. This is not the game's first iteration. Before the current version, an older build existed—with different rules, a different map, and even subtle deviations in the laws of physics. Most of that legacy data has been purged, but one "person" slipped through the deletion process and remains.