https://store.steampowered.com/app/297350/The_Old_City_Leviathan/
The Old City: Leviathan is an experiment in first person exploration that focuses entirely on story. All that exists is you and the world. Set in a decaying city from a civilization long past, The Old City: Leviathan puts the player in the shoes of a sewer dwelling isolationist.

The key has no territorial restrictions - REGION FREE and is suitable for activation in any country.