Here is the full list of all 12 WonderCat Adventures achievements.
Defeat the boss in Old Crystal Mine
Defeat boss in Clouds world
Defeat boss in Toxic Pipes
Defeat boss in Molten Core mines
Defeat boss in Elemental Chambers
Get all crystals on World 1
Get all crystals on World 2
Get all crystals on World 3
Get all crystals on World 4
Get all crystals on World 5
Get all crystals !
Win level 3.3 in less than 20 seconds