Monster Machines Hidden Letters is a Puzzle game on PFreeGames.com. You can play Monster Machines Hidden Letters in your browser for free. 26 letters are hidden in the cool monster machines. Can you find the letters in limited time. There are three monster machines in the game. If you need more time, you can turn off the time limitation. Five mistakes are allowed. Enjoy the Monster Machines Hidden Letters. Control: Use mouse to play this game.