Here is the full list of all 12 Elemgate Demo achievements.
Complete level 1 on easy difficulty.
Complete level 2 on easy difficulty.
Complete level 3 on easy difficulty.
Complete level 1 on Normal difficulty.
Complete level 2 on Normal difficulty.
Complete level 3 on Normal difficulty.
Complete level 1 on Hard difficulty.
Complete level 2 on Hard difficulty.
Complete level 3 on Hard difficulty.
Collect an egg on each stage of level 1
Collect an egg on each stage of level 2
Collect an egg on each stage of level 3