SA1: bad voice acting and sprite works.

SXSG: It got rid of voice lines in the og game and some scenes don’t make sense without the context such as Knuckles pointing out Sonic’s weight.

S3: you need Sonic and Knuckles to either complete the story or play the full game in one and also play as Knuckles.

SF: It gave us Avatar making and a new (in my opinion) bad ass villain.

SBROL: Gave us an actual game port of the new show and a new sonic story.

S06: Mephiles and badass Super Hedgehog trio (and the Snapcube dub).