This shirt is on a fine line.
Certainly, it is a cool design. It is the Sonic face from the Sonic Team logo, but composed of 'pixels' which are each the old Genisis Sonic sprites in different positions. So it's a Sonic face composed of tons of different very tiny Sonics. It was made by an Archie Comics official artist, though it is not Sega licensed...it falls under those artists' ability to create Sonic drawings from scratch and then sell them off to the fans later. Because the artist is official it's not technically a bootleg, where otherwise it would be. Still, it is available at SharkRobot.com in 2009 in multiple sizes.