what is the design pattern used in space shooter

in space shooter tutorials i have experiences a very excellent design pattern whether its the games object in hierarchy view or in project view. every thing is well organized. i liked that design model i wanted some one to tell me what model it was that is been shown in the tutorials because i want to learn more about it. and i wanted to use it for my university project. all i need is the name and some additional information on it if its 2 tier or 3 tier or n tier...! thanks ..