Here is the full list of all 25 TRISTOY achievements.
complete the game
finish the game without dying
kill the parasite
find 7 treasure chests
bring Milo a heart
kill Maguja
kill the spider sarcophagus
use gyromantic magic
Oops!
get yourself a weapon
get roasted in the iron smelt
spend some time in the elevator
play Tristoy with a friend next to you
escape with Freedan, Stayn and Ink
betray your friend at the end
complete the game in less than 90 minutes
beat the sphinx in a riddle contest
die ten times in the trap room
die twenty times in the trap room
die fifty times in the trap room
kill Fren Gidius, Kaya and Falis
rescue a prisoner
kill one thousand shadowblobs
confess that you're a naughty boy
Jump more than 10000 times