Here is the full list of all 13 Alicemare achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Find the Cheshire Cat ending
Choose Stella
Choose Joshua
Choose Chelsy
Choose Letty
Think of another answer to the river puzzle
Look the true end
Speak to Cliff on the phone
Find the extra scene
Play Stella's piano
Reach level 7 in NuTetris
Look under the Joshua's bed
Eat the poisonous mushrooms