† Previously available in Sega Genesis Collection.
According to Ethan Einhorn, the producer for the collection, the three "lock-on" games (Knuckles in Sonic 2, Sonic 3 & Knuckles, and Blue Sphere) were not included citing "tight development times", and that including them would have meant "dropping several titles from the collection altogether", specifically the aforementioned nine unlockable games since "they all required unique emulation solutions".
Sonic's Ultimate Genesis Collection received "generally favorable" reviews, according to review aggregator website Metacritic.67
"Sonic's Ultimate Genesis Collection for PlayStation 3 Reviews". Metacritic. Archived from the original on April 15, 2012. Retrieved October 4, 2017. https://www.metacritic.com/game/sonics-ultimate-genesis-collection/critic-reviews/?platform=playstation-3 ↩
"Sonic's Ultimate Collection for Xbox 360 Reviews". Metacritic. Archived from the original on June 26, 2012. Retrieved October 4, 2017. https://www.metacritic.com/game/sonics-ultimate-genesis-collection/critic-reviews/?platform=xbox-360 ↩
Gerstmann, Jeff (February 16, 2009). "Sonic's Ultimate Genesis Collection Review". Giant Bomb. Archived from the original on October 4, 2017. Retrieved October 4, 2017. https://www.giantbomb.com/reviews/sonics-ultimate-genesis-collection-review/1900-113/ ↩
Miller, Greg (February 12, 2009). "Sonic's Ultimate Genesis Collection Review". IGN. Archived from the original on September 20, 2015. Retrieved October 4, 2017. http://www.ign.com/articles/2009/02/12/sonics-ultimate-genesis-collection-review ↩
Orry, Tom (February 19, 2009). "SEGA Mega Drive Ultimate Collection Review". VideoGamer.com. Archived from the original on October 4, 2017. Retrieved February 19, 2009. https://www.videogamer.com/reviews/sega-mega-drive-ultimate-collection-review ↩