Here is the full list of all 16 Army of Pixels achievements.
Win a game
Win 100 games
Unlit the torches on the menu screen
Kill a plant with a zombie
Have 100 gold in the game
Have 100 mana in a game
Complete all quests
A battle between an angel and a demon
Win a game in 5 turns
Win a game only with Tier 1 minions
Play five creature with manadigger trait
Play five creature with golddigger trait
Kill an enemy Tier 3 minion with rats
Revive 5 dead creature with the Raise Dead spell
Cast Turn to Bat spell on a bat
Your minion dodge 3 times in a row