No missable achievements (plus 18 unknown)
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Burnt a log bridge in Green Hill Zone
Spun a Star Post 10 times by going fast
Defeated a Rexon with the Walker Legs in Lava Reef Zone
Beat the game (any ending)
Found and rode all the boats in Hydrocity Zone Act 1
Had Shutterbug take 10 photos
Uncovered two item boxes with a single Goal Plate
Collected all seven Chaos Emeralds
Got a 3 chain combo in Chemical Plant Act 2 or in Mean Bean mode
Flown through a ship window in Flying Battery Zone Act 2
Found the barrel that leads to a Special Ring in Mirage Saloon Zone Act 2
Found the hidden room in Press Garden Zone and destroyed all breakable crates as Sonic
Collected all silver medallions in Bonus stage
Activated and destroyed eight simultaneous Eggmins during Metallic Madness Zone Act 2
Beat Titanic Monarch Zone Act 1 without taking a single hit
Found the secret submarine in Oil Ocean Zone Act 2
Collected all gold medallions in Bonus stage
Got to the Stardust Speedway Zone Act 2 tower in under a minute