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