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