by Zivouhr » Wed Sep 17, 2014 4:06 am
Bring the sprites into an editor program like Gimp or Photoshop, then either separate them into equally sized square frames (or rectangles if you like all the same size) and label each frame of animation starting with "sonic01", then "sonic02", etc for the other frames if he's walking right.
There have been a few projects on Sonic with Game Editor, and you can probably get better ideas through those threads on how to progress. Best of luck!
Sonic Games: By Sonic Team
I recently played Sonic 1, 2, 3 and Sonic & Knuckles again on the PS3 HD versions, having originally completed all the games back on the Genesis way back when. The only stages I wasn't a fan of were the underwater stages, which totally holds Sonic back from his fast paced run. Then you have to try and get breathe, can't always turn into a ball when falling in the water, and end up hitting an enemy and losing your coins.