Here is the full list of all 11 Squishy the Suicidal Pig achievements.
Kill all bosses on insane difficulty
Find the secret artifacts in space world
Complete a speedrun in less than an hour
Complete all levels!
Collect all the apples in game
Kill The Devil on insane difficulty
Kill the first 3 bosses on Hard mode!
Kill Frosty the Snowman on insane difficulty
Kill the Big Bull-y on insane difficulty
Kill Jesse "Boom" Coyote on insane difficulty
Survive atleast 88 seconds in the survival minigame