Full list of all 49 Sonic Generations achievements worth 1,000 gamerscore. It takes around 20-25 hours to unlock all of the achievements on Xbox 360.
Took no damage from the final boss and cleared the stage.
Got all collectibles.
Got all Skills.
Got all Red Star Rings.
Got the Red Star Ring by using an Orange Wisp in PLANET WISP Act 2 and reached the goal.
Got the Red Star Ring located in the hidden room in SEASIDE HILL Act 1 and reached the goal.
Got the Red Star Ring located on the shortcut route in SPEED HIGHWAY Act 2 and reached the goal.
Played Ranking Attack on all stages.
Cleared CHEMICAL PLANT Act 2 without entering the water.
Wrecked 30 or more cars in CITY ESCAPE Act 2.
Found the spring hidden in GREEN HILL Act 1 and reached the goal with a Red Star Ring.
Cleared GREEN HILL Act 1 within one minute.
Cleared a regular stage as Super Sonic.
Cleared Sonic Generations.
Collected all the Chaos Emeralds.
Defeated Egg Dragoon.
Cleared all the Challenge Acts.
Defeated Silver.
Completed all Challenge Acts featuring Sonic's friends.
Got Rank S in all Acts.
Chatted with all of Sonic's friends you saved.
Restored the PLANET WISP Stage Gate.
Restored the ROOFTOP RUN Stage Gate.
Got the Red Star Ring atop the highest spot in ROOFTOP RUN Act 2 and reached the goal.
Restored the CRISIS CITY Stage Gate.
Reached the goal in CRISIS CITY Act 2 without being hit by a tornado-carried cars or rocks.
Participated in a 30 Second Trial.
Defeated Perfect Chaos.
Cleared half the Challenge Acts.
Got Rank S in twelve Acts.
Defeated Shadow.
Restored the SEASIDE HILL Stage Gate.
Performed all of Sonic's actions in Act 2.
Restored the CITY ESCAPE Stage Gate.
Got Rank S in seven Acts.
Cleared SKY SANCTUARY Act 1 without falling and losing a life.
Restored the SPEED HIGHWAY Stage Gate.
Defeated Death Egg Robot.
Got Rank S in three Acts.
Pulled off a seven or more trick combo or six trick combo ending in a finishing trick.
Defeated Metal Sonic.
Restored the SKY SANCTUARY Stage Gate.
Got Rank S in an Act.
Reached the goal without dropping any of the rings you collected in GREEN HILL Act 1.
Defeated 100 enemies.
Restored the CHEMICAL PLANT Stage Gate.
Joined the rankings.
Restored the GREEN HILL Stage Gate.
Completed the first stage.