Read about All the Endings in The Sinking City
The Sinking City endings
The first ending: Repeat Cycle and Charles Death
Come to the last room, go left. There you need to look at the past and go to the edge. You will see how the main character sacrifices himself. After that you will see the ship and Vand Der Berg. This means that all events in the game are repeated again.
The second ending: Cycle Interruption and Charles Death
You need to put a stamp on the central platform. The door ahead will open, and a giant creature will devour the hero. After you see how a huge tsunami is heading for Oakmont. This means the complete destruction of the world.
The third ending: Interrupting the cycle and Saving Charles
Go to the right wing. Charles interrupts the cycle and leaves. Five years later, he drinks in a Boston bar. Soon he notices that people are starting to go crazy, and the flood also begins. Apparently, due to the fact that the main character decided to retreat, the events of Oakmont begin to occur in Boston.