Bio World is Back in Modern!
Modern design...that is! Bio World has long been a good maker of Sonic clothing, and creator of some fan-favorite designs. They put actual effort into things they do (most of the time) but the boom ban had them either gone or only doing the very occaisional & simple classic style tee.
This could be their first tee 'back in action', as it appears in spring 2019 at Amazon (but maybe elsewhere) It's an all black teens/boys size tee with large faded Sonic portrait. Overlayed in the portrait are lots of big square 'pixels', and full body images for Tails, Shadow, Knuckles & a running Sonic. The grahpic is kind of 'Sonic X' reminiscent in style. The 'outer space' look & overlay effect is nice, modern & a colorful character showcase. There are no other tees that look a lot like it, so it's a good find. However, it is 21 dollars which is a tad high for a 'kids/teens' size.

At the right you have the shirt that is called the "Sonic Spotlight Rings Tee".
The black shirt has a small full color modern Sonic 'thumbs up' stock art toward one side. The main graphic of the tee is a stencil effect/spray effect "shadow" of him cast onto the blue 'background' of foggy color. There are a few faint ring shapes scattered around back there too (but why?) It's a fun enough concept, to make the cast-shadow the star of the show.
Brush up on the classics? This isn't the first time it's been done. There's actually a classic tee with classic Sonic that was pretty rare that did a similar effect, but not to this scale. That shirt is in the SonicGear collection & you can see it here at the site too. This is an Amazon item for 21 dollars in 2019/spring season.