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