I can see something here, a canvas to improve upon and make a high paced platformer beat em up.
The main problems i have with the game is the limited screen size, which makes hard to see incoming enemies or platforms, making you either take leaps of faith or tip toe across the game (which for a character as fast as Sonic doesnt mesh well with). The enemies had a tad much health and your punches have way too much knockback, so its hard to combo enemies unless you pin them to a wall, while doing so they can squeeze around you and sneak in a hit and its just a bit sloppy.
The drawings are decent and look good, a couple more frames of animation wouldnt have hurt. Also a limit or little more variation on Sonics grunts and screams would´ve make him more tolerable.