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 5000 gold
Finish all quests
Beat Moonface
Beat the mountain boss
Reach 0 gold
Beat the mangrove boss
Buy all life extensions
Beat the seaside boss
Beat the desert boss
Loose 10 times
Beat the cave boss
Use the thunder orb
Beat the swamp boss
Use the ice orb
Beat the forest boss
Make 20 mistakes
Beat the plains boss
Use a potion
Use the fire orb
Have a full inventory
Beat the village boss
Finish a three-monster grid
Finish a two-monster grid
Finish a one-monster grid
Read the tutorial
Finish the first grid