Complex sentence: It is the first handheld console in the Game Boy line, and was created by Gunpei Yokoi and Nintendo Research & Development 1--the same staff who had designed the Game & Watch series as well as several popular games for the Nintendo Entertainment System.
Split into simpler sentences: It is the first handheld console in the Game Boy line and was created by Gunpei Yokoi and Nintendo Research & Development 1. This is the same staff credited with designing the Game & Watch series as well as several popular games for the Nintendo Entertainment System.