Prison Architect is a prison management sim. Starting with an empty plot of land you must construct a holding cell with basic water and electricity to house your first batch of prisoners. You'll need to hire some guards, get some showers built, and unless the kitchen is up and running with chefs working away, you're going to end up with a riot on your hands. From there you take your prison in whichever direction you like. A monstrous super-max or comfortable center for rehabilitation, the choice is up to you.
Prison Architect is currently in Alpha which means that the game is playable, but still in development. Not all features are implemented yet and there are many bugs that may affect gameplay.