Here are the twenty-seven secret achievements you can unlock in Sonic Generations for the Xbox 360.
Check out my other guide if you’re looking for the complete list of unlockable achievements in Sonic Generations.
A Quick Breather (10) – Got the Red Star Ring atop the highest spot in ROOFTOP RUN Act 2 and reached the goal
Boom Boom Dragoon (30) – Defeated Egg Dragoon
Can’t Touch This (30) – Took no damage from the final boss and cleared the stage
CHEMICAL PLANT Restored! (15) – Restored the CHEMICAL PLANT Stage Gate
CITY ESCAPE Restored! (15) – Restored the CITY ESCAPE Stage Gate
Color Power! (10) – Got the Red Star Ring by using an Orange Wisp in PLANET WISP Act 2 and reached the goal
CRISIS CITY Restored! (15) – Restored the CRISIS CITY Stage Gate
Demolition Derby (10) – Wrecked 30 or more cars in CITY ESCAPE Act 2
GREEN HILL Restored! (15) – Restored the GREEN HILL Stage Gate
Jump for Joy! (10) – Found the spring hidden in GREEN HILL Act 1 and reached the goal with a Red Star Ring
Look Both Ways (10) – Reached the goal in CRISIS CITY Act 2 without being hit by a tornado-carried cars or rocks
Perfect Punisher (25) – Defeated Perfect Chaos
PLANET WISP Restored! (15) – Restored the PLANET WISP Stage Gate
ROOFTOP RUN Restored! (15) – Restored the ROOFTOP RUN Stage Gate
Scrap Metal (20) – Defeated Metal Sonic
SEASIDE HILL Restored! (15) – Restored the SEASIDE HILL Stage Gate
Secret Sleuth (10) – Got the Red Star Ring located in the hidden room in SEASIDE HILL Act 1 and reached the goal
Shadow Boxing (25) – Defeated Shadow
Silver Got Served (30) – Defeated Silver
SKY SANCTUARY Restored! (15) – Restored the SKY SANCTUARY Stage Gate
SPEED HIGHWAY Restored! (15) – Restored the SPEED HIGHWAY Stage Gate
Sunny Side Up (20) – Defeated Death Egg Robot
Supersonic! (20) – Cleared a regular stage as Super Sonic
The Byway or the Highway (20) – Got the Red Star Ring located on the shortcut route in SPEED HIGHWAY Act 2 and reached the goal
Treasure Hunter (20) – Collected all the Chaos Emeralds
Walk on Air (20) – Cleared SKY SANCTUARY Act 1 without falling and losing a life
Walk on Water (10) – Cleared CHEMICAL PLANT Act 2 without entering the water