Lord of Summons! Sudden Mutation

The apocalypse came. Monsters inside the game broke through the dimensional barrier and started a massacre, driving human civilization on the Blue Planet to the verge of destruction. At the last moment of collapse, his time was suddenly rewound back to the moment the game first appeared. Now he is dedicated to finding out the one behind this, protecting his home and preventing the tragedy from happening again. Thus, a game of revenge begins, racing against time...