Special Features: Unlimited Ammo. Instructions: A "trainer" is a third-party program that is designed to alter memory locations of running programs (games). In order for a trainer to work, it must be running simultaneously with the game it was written for. It is best to first start the game and actually begin playing, then switch back to Windows (using Alt+Tab) and run the trainer. Select the desired options and switch back to the game. Do not CLOSE the trainer until you are finished playing the game. Since trainers are written to alter SPECIFIC memory locations, they usually only work with specific versions of the game. This is the most common problem when trainers seem to be "not working".