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