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