Here is the full list of all 15 The Fading Worlds achievements.
Begin playing Fading Worlds
Get your Prisma
Travel between worlds for the first time
Meet "Helena"
Kill the first Old One
Travel to Central World for the first time
Meet "Ayane"
Kill the second Old One
Beat the Hollow King
Kill the Third Old One
Travel to Sky World for the first time
Kill the Fourth Old one
Violence that not the only way
Build the Ultimate Weapon of Destruction
Get to the Final World