Here is the full list of all 18 Solstice achievements.
Get intimate with an ex-killer.
Find out what happened to Lev.
Play it safe when talking to strangers.
Just relax and enjoy the baths.
Make a promise to someone you barely know.
Pay attention to Galen's mentor.
Let Yani be the doctor for once.
No dog should see this...
Bring the murderer to justice.
Seek magic and power hard enough.
Receive assistance from someone who trusts no one.
Make the final choice.
Save the day like a true hero.
Keep it warm and natural.
Leave a mark on the wasteland.
Let the Winter win.
Abandon your goals.
Experience all possible endings.