Start with the Unity examples until you know enough about game objects, rigid bodies, collision detection. You could mock up a simple 2D game with basic shapes for prisoners, guards, etc. Give your player control of one object and his goal is to escape the maze/facility. This would be done with simple OnTriggerEnter or OnCollision events for reaching certain areas of the map. Next, add AI for guard patrols and what happens if you get caught or make it out (game over and victory conditions).