Here is the full list of all 27 GNOSIA achievements worth 1,000 gamerscore.
Obtain all achievements
Unlock all of Gina's special items
Unlock all of SQ's special items
Unlock all of Raqio's special items
Unlock all of Stella's special items
Unlock all of Shigemichi's special items
Unlock all of Chipie's special items
Unlock all of Remnan's special items
Unlock all of Comet's special items
Unlock all of Yuriko's special items
Unlock all of Jonas' special items
Unlock all of Setsu's special items
Unlock all of Otome's special items
Unlock all of Sha-Ming's special items
Unlock all of Kukrushka's special items
Enter a world with 0 Gnosia
Reach the ending
Reach the true ending
All crew members appear
Unlock all roles
Acquire all skills
Win while playing as a Human with 6 Gnosia
Win while playing as a Guardian Angel and successfully protect a crew member twice in one loop
Win while playing as an Engineer and discover Gnosia three times in one loop
Win while playing as an AC Follower and announcing your role under unfavorable conditions
Win while playing as the sole Gnosia in a loop with 15 crew members
Win while playing as a Bug and announcing your role under unfavorable conditions