Enhancements:
●Added Anitquity Zone, HSZ5
●Added "Press Start to Skip/Continue" text on SEGA screen
●Created new Title Screen and ROM info, better graphics for Level Select menu
●Added highlight to solid blocks and fixed palette issues in BZL
●Added rings to beginning of all levels
●Created better "V" letter, and indicator for FG or BG layer in BZF for Title Cards
●Gave Title Card its own song
●Added loop to invincibility song

Bug Fixes:
●Fixed warp issues with returning back to a standard platform level after special stages
●Improved collision slightly for elbow and S-ramps, quarter pipes (still not perfect)
●Fixed issue with dying at top of level
●Fixed issue with falling through chunk solidarity if falling too fast
●Fixed issue with extended playlist not playing if on and after using invincibility/nearly drowning
●Imported better graphics for various objects
●Enabled priority for all moving spikes
●Re-enabled and fixed animals in HSZ, BZF, and SAZ
●Improved collision with touch-pop monitors
●Various minor objpos changes in levels
●Other bugs/user-reported issues I can't remember

Gave (myself) official permission to upload (my own) hack.
See
http://sonicresearch.org/community/index.php?threads/socket-the-hedgeduck-demo-v0-2.4342/page-4#post-68218

v0.2 Changes:
Uploaded hack to Sega Mega Drive & Genesis Classics as a workshop item.

See following link for full changelog:

http://sonicresearch.org/community/index.php?threads/socket-the-hedgeduck-demo-v0-2.4342/page-4#post-68110