No missable achievements (plus 15 unknown)
Sign in with Steam or Xbox to track your progress, and:
Become friends with Tails.
Become friends with Knuckles.
Become friends with Amy.
Become friends with E-102.
Become friends with Big.
Clear the Sonic story.
Clear all characters stories.
Get all Emblems in the Adventure Field.
Get all Emblems of the Chao Race.
Get all Emblems of the Sub Games.
Get Level A on all the Action Stages.
Get all 130 Emblems.
Get all 130 Emblems by playing Sonic Adventure DX.
Clear all 60 missions.
Get Level A on all the Action Stages by using Metal Sonic.