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