Here is the full list of all 50 I Was a Teenage Exocolonist achievements.
Get the Transcended Time Ending
Get the Joined the Gardeners Ending
Negotiate with the Gardeners at the end of age 19
Get the Life on Earth Ending
Unlock Tangent on the Main Menu
Help Nomi confess their love to Rex
Unlock Sym on the Main Menu
Stop Tangent's engineered plague
Get the Ran Away Ending
Unlock Dys on the Main Menu
Kill a Faceless
Unlock Anemone on the Main Menu
Break up Anemone and Vace
Reach 100 Rebellion skill
Unlock Tammy on the Main Menu
Saved Uncle Tonin
Replace Governor Lum
Get 5 relationships to 5 hearts
Prevent Cal and Tammy from dating
Saved Professor Hal
Helped Tangent cure the Shimmer disease
Ended the famine
Start your second life
Saved Tammy
Meet Sym the Gardener
Unlock Cal on the Main Menu
Pet your Pet
The Helios Lands in age 15
Sneak Out to explore
Win a Vertumnalia event
Reach the end of age 10
Reach 100 in all 4 skills of one type
Get the Disabled the Array Ending
Get the Tangent's Cure Ending
Get the Colony Destroyed Ending
Get all 29 Endings
Unlock Marz on the Main Menu
Unlock Rex on the Main Menu
Unlock Nomi-Nomi on the Main Menu
Unlock Vace on the Main Menu
Unlock all characters on the Main Menu
Own four different pets at once
Score 75 in a single hand
Get a single card to value 50 or higher
Win 10 card games in a row in hard mode
Get a flush of five 5s
Win an Impossible challenge in hard mode
Have a deck of cards of a single color or wildcards
Unlock every card in the gallery (a lot more than 151)
An experimental treatment for your delusions