Answer: Jet Set Radio

Cel-shading is a manner of rendering 3D computer graphics in such a way as to make them appear as if they had been hand drawn like animation cells.

The first video game to make use of cel-shading, and a critically acclaimed title in its own right, was SEGA’s Jet Set Radio, released for the Dreamcast in June of 2000.

Since then over 250 video games rendered in cel-shading style have been released including several notable modern games like those in the Borderlands series, the Ōkami series, as well as The Legend of Zelda: The Wind Waker, Bastion, and Mad World.