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.
Find the hidden fort in Wholesale.
Complete all pursuit courses.
Complete all courses and trials in Wholesale.
Complete all courses.
Unlock all courses in Wholesale.
Use a water fountain.
Unlock all courses in School.
Complete all courses and trials in School.
Complete all Pogo trials.
Complete all Tiny Toy trials.
Complete all courses and trials in Playground.
Complete all courses and trials in Basement.
Unlock all courses in Basement.
Complete all courses and trials in Master Class.
Unlock all courses in Master Class.
Unlock all courses in Playground.
Complete a community map course.
Get a basketball into the hoop in Playground.
Pick up a pair of scissors and run with it.
Pick up a knapsack and run with it.
Jump 5000 Times.
Complete a course with Buddy.
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.
Lose Buddy to the lava.
Complete the Intro.
Complete the first course in Tutorial.
Jump 100 times.
Jump 1000 Times.
Perform a "late" jump right after leaving a ledge 77 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.