This is called the "Retro Red" Sonic shirt.
But, the shirt isn't red, it's a lightly mottled blue. Sonic is done in a pale grayish blue, navy blue (for nose & eyes) and white instead of beige. Only his shoes are red, along with the background for his name at the top in a red rectangle. The art is forward facing, pointing up, neo-classic Sonic.
The thing to note is that the "Sonic" word in that font, spelled out inside the red rectangle with white letters is made to resemble the logo of a different fashion brand/probably something expensive. It's probably no accident the art they chose has him pointing up at it. What brand writes the name in white on red and looks kind of like that? You can write in for credit. This is a Bio World adults sizes tee shirt.