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