Prayers of Armageddon

Prayers of Armageddon is a Doom II megawad created by Santtu Pesonen (MFG38). It includes 32 new maps and a hidden bonus map which is only accessible via using cheats. All the levels for the megawad were created entirely by Pesonen. There was also a remake titled Prayers of Armageddon: Retaliation, and it was released in 2014.