Here is the full list of all 41 Hot Lava achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Unlock a follower.
Complete one sticker set.
Pick up a pair of scissors and run with it.
Pick up a knapsack and run with it.
Complete a course with Buddy.
Lose Buddy to the lava.
Complete a community map course.
Complete all courses and trials in Wholesale.
Complete all Tiny Toy trials.
Find the hidden fort in Wholesale.
Complete all Pogo trials.
Get a basketball into the hoop in Playground.
Complete all courses and trials in Basement.
Complete all pursuit courses.
Complete all courses.
Unlock all courses in Basement.
Jump 5000 Times.
Tweak something in the Options menu.
Complete all courses and trials in Master Class.
Unlock all courses in Master Class.
Unlock all courses in Wholesale.
Unlock all courses in School.
Complete all courses and trials in School.
Use a water fountain.
Complete all courses and trials in Playground.
Unlock all courses in Playground.
Jump 1000 Times.
Die by Collision.
Complete your first "pursuit" course.
Complete all courses and trials in Tutorial.
Unlock all courses in Tutorial.
Build up boost to 5 m/s.
Complete a Pogo trial.
Complete a Tiny Toy trial.
Complete all challenges for a single course.
Perform a "late" jump right after leaving a ledge 77 times.
Complete a course with no deaths.
Complete the first course in Tutorial.
Unlock your first character.
Jump 100 times.
Complete the Intro.