Genesis Sonic Engine v1.3 by @tomicool
Instructions are in game. Following is an update log:
Version 1.3 (10th September, 2015)
- Sonic can enter rolling a tad earlier and ends rolling a tad later

(music is "Air Time" from Trackmania 2; Sonic sprite courtesy of t0ms0nic)

I made this little project in the Spring of 2014 for my GCSE IT assignment.