Here is the store poster for Sonic Pocket Adventure game.
It's for the "Neo Geo Pocket Color", which was a portable game system that didn't really succeede for that long. The poster is a little confusing too. It shows SA1 wierd walking Sonic, but then look at the screen shots they show you in the bottom right: Those are Sonic 2 things, like the half-pipe special stage.

The headline up there (can't read it) may explain it a little bit, but it may not be a wonder it wasn't a success if it says Pocket Adventure, cribs the SA1 logo, uses SA1 art, and then delivers Sonic 2 looking content. (Remember, this was 1999 when it came out, Sonic going into "3d" instead of side-scrolling was a big deal then) The game itself WAS a success, as critics rated it really well. It used elements like music & style from earlier Sonic games, had a vs. race mode (link cable) & a few puzzles too. This poster is an interesting relic of the old system.