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