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 a community map course.
Complete one sticker set.
Unlock a follower.
Complete all courses and trials in Basement.
Complete all Pogo trials.
Complete all Tiny Toy trials.
Complete all pursuit courses.
Complete all courses.
Unlock all courses in Basement.
Complete all courses and trials in Master Class.
Jump 5000 Times.
Unlock all courses in Master Class.
Get a basketball into the hoop in Playground.
Complete a course with Buddy.
Lose Buddy to the lava.
Find the hidden fort in Wholesale.
Complete all courses and trials in Wholesale.
Unlock all courses in Wholesale.
Unlock all courses in School.
Complete all courses and trials in School.
Complete all challenges for a single course.
Use a water fountain.
Pick up a pair of scissors and run with it.
Pick up a knapsack and run with it.
Complete all courses and trials in Playground.
Unlock all courses in Playground.
Jump 1000 Times.
Die by Collision.
Complete a Pogo trial.
Complete all courses and trials in Tutorial.
Complete a Tiny Toy trial.
Complete a course with no deaths.
Complete your first "pursuit" course.
Unlock all courses in Tutorial.
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.