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