Donkey Kong - Arcade Rainbow is a hack of the original Donkey Kong arcade game. Hacks modify existing games, often changing visuals, sound, or gameplay mechanics.  In this case, 'Rainbow' likely refers to a visual alteration, possibly involving modified color palettes or visual effects.  Because it's a fan-made modification, it was not officially created or released by Nintendo and it's important to distinguish it from the original.

Donkey Kong - Arcade Rainbow (hack)

Don Doko Don (US)