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