All achievements can be gotten in 4 playthroughs which will take around 4 hours depending on how you decide to play.
Necklace of Storms
Get any ending as Saturn
Sea of Crises
Get any ending as Luna-Terra
Eye of the Underworld
Get any ending as Pluto
…Our True Ending
Beat the game as each character once
The New Planets
Side with Celestial Mechanics
Moving The Decimal Place
Side with the Memorial Foundation
Side with Cradle’s Graces
That Which Is Strong Will Not Triumph
Get all three endings (CM, MF, CG) as any character(s)
Good At Bad Decisions
Click any alignment option for the first time
Subtext Is For Cowards
Read all chats in the “Comms” tab on all three characters
Hint : New chats appear after every mission, click through until you get the “Channel Closed” message.
The Ending We Choose Is…
Find a way to make sure everyone is equal
Hint: Make sure your alignment with all three factions is 50/50/50 by the final day, you can check the “Alignment” tab to see your exact standings. This ending will allow you to pick from any of the three faction endings regardless of choices or character.
I’ve Never Betrayed Anyone In My Entire Life
Side with Celestial Mechanics or Cradle’s Graces as Luna-Terra can also be achieved with the neutral ending if you don’t pick MF.