Here is the full list of all 17 Tiny Chaos Demo achievements.
Open your first chest
Open 7 chest before fighting the boss
Reach level 15
Reach level 30
Reach level 50
Kill 500 enemies in one play
Kill 1000 enemies in one play
Kill 2500 enemies in one play
Kill Goblin King on Hard Mode
Kill Ogre
Kill Blue Ogre
Kill Black Ogre
Earn 1000 Points in one play
Earn 2500 Points in one play
Earn 5000 Points in one play
Earn 10000 Points in one play
Earn 15000 Points in one play