Here is the full list of all 26 PictoQuest achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Reach 0 gold
Finish all quests
Beat Moonface
Buy all life extensions
Beat the mountain boss
Reach 5000 gold
Beat the mangrove boss
Read the tutorial
Beat the seaside boss
Loose 10 times
Beat the desert boss
Use the thunder orb
Use the ice orb
Use the fire orb
Use a potion
Beat the cave boss
Beat the swamp boss
Beat the forest boss
Have a full inventory
Make 20 mistakes
Beat the plains boss
Beat the village boss
Finish a three-monster grid
Finish a two-monster grid
Finish a one-monster grid
Finish the first grid