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