Here is the full list of all 48 Sonic Forces achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Collected a total of 100,000 rings. (All Rings held at the end of the stage will be counted.)
Collected all Silver Moon Rings in Shadow's Story.
Collected all Number Rings in Shadow's Story.
Collected all Red Star Rings in Shadow's Story.
Collected all Wispons
Collected all parts
Achieved highest honors with all races
Completed all Challenge Missions
Collected a total of 50,000 rings. (All Rings held at the end of the stage will be counted.)
Defeated 10,000 enemies
Cleared all EX Stages
Collected all Silver Moon Rings
Collected all Number Rings
Collected 500 parts
Collected all Red Star Rings
Defeated 5,000 enemies
Completed 10 SOS Missions
Collected Silver Moon Rings three times
Collected Number Rings three times
Completed 10 Daily Missions
Collected 30 Wispons
Cleared all Secret Stages
Completed 5 SOS Missions
Collected a total of 10,000 rings. (All Rings held at the end of the stage will be counted.)
Created your second Avatar
Achieved a soldier's highest honor
Completed your first SOS Mission
Utilized the Rental Avatar function
Made it into the rankings
Used the Closet
Restored peace to the world
Completed 5 Daily Missions
Defeated Infinite
Completed 3 Daily Missions
Collected 10 Wispons
Turned the tide of the conflict
Equipped a part in every slot
Drove off Infinite again
Defeated 1,000 enemies
Liberated a world
Collected 100 parts
Drove off Eggman
Drove off Infinite
Collected 50 parts
Changed Wispons for the first time
Defeated Zavok
Created an Avatar
Cleared Stage 1