Here is the full list of all 16 Chaos Crown Demo achievements.
You killed an enemy with Deathtouch.
You hit three enemies with Arrow Spray.
You overkilled an enemy with the Lava Elemental.
You passed through the ground! Sorry about that.
You burned 20 enemies!
You drinked 20 potions.
You retreived the Divine Coin 10 times.
You completed a level with the Greedy Malus.
You completed a level within 20 minutes.
You completed a level within 30 minutes.
You found a room filled with 3 treasure chests.
You collected 10 Fire Gems.
You completed a level with the Archer.
You completed a level with the Lava Elemental.
You made a deal with a Chaos Lord.
You reached the movement speed cap.