Here is the full list of all 12 Curse of the Old Gods achievements.
The Coin wasn't strong enough to close the Portal.
You've wished for a walkthrough.
You tried to save the world with empty hands.
You've reached the maximum score.
Save the world from the Old Gods.
You've tried to shoot Clayton in the face.
You've saved Miguel's life.
You've tried to eat the giant lunch.
You've puzzled the pieces of paper together.
You've found the connection to the Illuminati.
You've found evidence that the nightwatchman was murdered.
You've found a nice hot cup of tea.