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