On top of that, the modeling layer adds the gameplay, so that players and objects interact. Finally, the interface displays the simulation to the screen so that the user can interact with it. The network layer manages the physical link between hosts in the session It hides the details of network protocols, packet formats, and addresses from the upper layers. The modeling layer is the most important part of the software, because it drives and enforces all of the gameplay logic. A simulation without any interface is pretty boring.
Most games let the user observe the world from a fixed point, or interact with it using an agent.
Selecting which game to play and changing player preferences. Describing the world to the user with text, 2D, or 3D graphics. Overlaying the graphic display with indicators and gauges. Adding to the experience with sound effects or music tracks. Checking for user input via keyboard, mouse, or joystick.