HES was a longtime Australian maker of unlicensed Atari 2600 games They also made many different 4 and 8 game multi-carts for the Atari. They did release one original game, My Golf, (programmed by David Lubar).
HES has given up their pirate ways and now produces peripherals for modern consoles. You can check out their website a www.hesinteractive.com.
HES Game Listing