You can use any text edit software to create a model. Of course, you will have to learn the programming language that Skyscraper uses. The app comes with some examples and a programming guide.
Skyscraper allows you to explore constructions and to travel through their surroundings. Use the elevator or the stairs to go up a level. The view is controlled with a number key and arrows. The Space Bar is to jump and Shift is to accelerate.
The simulator that controls the elevators is very interesting. It is controlled by clicking the option “Edit elevator” on the control panel. It allows you to open and close the doors manually, make an emergency stop, press the button for individual floors, etc.