Here is the full list of all 16 Phantom Trigger achievements.
Arena completed.
Do you know what insanity is?
Kill everyone
Congratulations, you skipped the story
Did you read the text at the very end of the game?
Beat all bosses in co-op mode
Chop down the tree
Take a trip with Pam
Turn off the last TV set
Smash all crystals
Solve all puzzles
Kill 50 frozen enemies
Unlock all combos
Kill 20 enemies in co-op mode
Die in co-op mode
The tree falls!