K.O. - The Pro Boxing ROM Download for Gameboy Color (GBC) on Emulator Games. Play K.O. - The Pro Boxing game that is available in the United States of America (USA) version only on this website. K.O. - The Pro Boxing is a Gameboy Color emulator game that you can download to your computer or play online within your browser. You can also download free ROMs such as Tony Hawk's Pro Skater 3, Ready 2 Rumble Boxing and Tony Hawk's Pro Skater 2 as shown below. K.O. - The Pro Boxing works on all your devices in high quality.