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.
Cleared CHEMICAL PLANT Act 2 without entering the water.
Cleared GREEN HILL Act 1 within one minute.
Cleared a regular stage as Super Sonic.
Played Ranking Attack on all stages.
Got all Skills.
Joined the rankings.
Participated in a 30 Second Trial.
Cleared Sonic Generations.
Got all collectibles.
Collected all the Chaos Emeralds.
Defeated Egg Dragoon.
Completed all Challenge Acts featuring Sonic's friends.
Cleared all the Challenge Acts.
Defeated Silver.
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 Rank S in all Acts.
Chatted with all of Sonic's friends you saved.
Restored the PLANET WISP Stage Gate.
Got the Red Star Ring atop the highest spot in ROOFTOP RUN Act 2 and reached the goal.
Restored the ROOFTOP RUN Stage Gate.
Reached the goal in CRISIS CITY Act 2 without being hit by a tornado-carried cars or rocks.
Restored the CRISIS CITY Stage Gate.
Defeated Perfect Chaos.
Pulled off a seven or more trick combo or six trick combo ending in a finishing trick.
Performed all of Sonic's actions in Act 2.
Defeated Shadow.
Cleared half the Challenge Acts.
Got the Red Star Ring located in the hidden room in SEASIDE HILL Act 1 and reached the goal.
Restored the SEASIDE HILL Stage Gate.
Got Rank S in twelve Acts.
Wrecked 30 or more cars in CITY ESCAPE Act 2.
Restored the CITY ESCAPE Stage Gate.
Got the Red Star Ring located on the shortcut route in SPEED HIGHWAY Act 2 and reached the goal.
Restored the SPEED HIGHWAY Stage Gate.
Got Rank S in seven Acts.
Defeated Death Egg Robot.
Defeated Metal Sonic.
Restored the SKY SANCTUARY Stage Gate.
Cleared SKY SANCTUARY Act 1 without falling and losing a life.
Restored the CHEMICAL PLANT Stage Gate.
Got Rank S in three Acts.
Defeated 100 enemies.
Found the spring hidden in GREEN HILL Act 1 and reached the goal with a Red Star Ring.
Reached the goal without dropping any of the rings you collected in GREEN HILL Act 1.
Got Rank S in an Act.
Restored the GREEN HILL Stage Gate.
Completed the first stage.