Hi, I'm Dan Cunningham

A Windows screen saver is basically just a standard Windows executable that has been renamed to have a .SCR filename extension. In order to interface properly, certain requirements must be met. In general, the program must:

• Distinguish between active mode and configuration mode
• Disallow multiple copies of itself to run
• Exit when the user presses a key or moves the mouse

Here a quick Delphi Tutorial on how to make a basic screen saver for windows.

View Tuturial: Delphi Tutorial Graphics – How to make a screen saver