DOS environment emulator for backwards compatibility with old games.
Xbox 360 emulator for Windows, experimental, free, requires powerful hardware.
Atari 2600 emulator which is considered the best emulator of this console.

Remember the classic Playstation 1 games on your computer screen.
Free and portable emulator of Atari 8-bit and Atari 5200.
Playstation 2 emulator for Android.