This was found as an easter egg in the terminal app of Mac where, within the app, one can play Snake or Tetris game. These are hidden games that someone would not find directly without the trick.

Follow these steps to open and play the games -

• Open the applications folder
• Open Utilities
• Open Terminal
• In the terminal app, type emacs and press enter
• Now in the emacs data you see in terminal, press X and hold down Esc* Now type any of the name of games which you want to play!

Like type snake to play snake game and enter
Type tetris and press enter to play the tetris game

These games do not come with the Mac OS but come with emacs which is a part of the UNIX system. These would not open in a new window or app, but comes within the terminal app window.