Here is the full list of all 25 Twofold achievements.
Finish the prologue
Finish Caprice Act 1
Finish Caprice Act 2
Finish Caprice Act 3
Finish Caprice's Epilogue
Finish Millie Act 1
Finish Millie Act 2
Finish Millie Act 3
Finish Millie's Epilogue
Experience all optional choices in the prologue
Join the art club, for better or worse
Join the writing club, or what little is left of it
Make Allison a promise (Befriend Allison)
Find a true friend in Darren (Befriend Darren)
Get the truth from Eileen (Befriend Eileen)
Listen to what Heather has to say (Befriend? Heather)
Help ease the guilt weighing Tanya down (Befriend Tanya)
Help Wallace find his place in the club (Befriend Wallace)
Browse the Guest Art gallery after unlocking it
Complete both key paths in Twofold
Start Perfect Circle for the first time
See Perfect Circle through to the end
Check in on Junebug
She has a name, you know
Obtained all other achievements. Thank you for following their stories.