NesEm is a NES console system emulator. You can play hundreds of NES games (also known as NES roms) with a single application. NesEm comes with two sample NES games. More games can be obtained separately and added to the application simply by placing them into the nesem folder on the Pre USB drive (if nesem folder does not exist, NesEm will ask you to manually create this folder under the root folder of the USB drive). NesEm Free can play the same roms as the paid version with no time-limits. However, it has the following limitations compared to the paid version. Full screen game play, save states, game cheats and configuration of keyboard controls are disabled.