Here is the full list of all 25 TRISTOY achievements.
complete the game
kill Maguja
find 7 treasure chests
betray your friend at the end
finish the game without dying
use gyromantic magic
Oops!
get yourself a weapon
bring Milo a heart
spend some time in the elevator
play Tristoy with a friend next to you
kill the spider sarcophagus
kill the parasite
escape with Freedan, Stayn and Ink
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
get roasted in the iron smelt
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