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