Frontier Castle Fort Occupation Battle - To occupy of the fortress (辺境城砦占領戦 - To occupy of the fortress) is an online game based on the Overlord series. It is a sequel to the game Great Tomb of Nazarick Survival Escape - The Escape from Nazarick. The release period of the game started on October 27, 2018.
The game is structured in a way that the player reenacts the events in which workers are raiding the Great Tomb of Nazarick.
The player becomes a member of Nazarick and carries out the first order from Ainz to prevent invaders from invading the tomb.
- This game was released as part of an "Overload III" Halloween fan event.