Mystique is a free screensaver program I wrote in FreeBASIC to simulate the old Dancing Lines screensaver in IdleWild from 1990. The screensaver was later included in Windows 95 with the name "Mystify," and continued to be included with Windows until it was replaced in Windows Vista where the name remained the same, but the program was quite different. Like Dancing Lines, the program displays several lines bouncing around the screen leaving trails behind them. I've added various forms of customization as well. Once you run the program, press the '?' key to see how to adjust the settings.
This includes the program and source code.