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 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.
Find the hidden fort in Wholesale.
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.
Complete a community map course.
Pick up a pair of scissors and run with it.
Jump 5000 Times.
Complete all courses and trials in School.
Unlock all courses in School.
Use a water fountain.
Complete all courses and trials in Playground.
Unlock all courses in Playground.
Pick up a knapsack and run with it.
Complete a course with Buddy.
Get a basketball into the hoop in Playground.
Complete your first "pursuit" course.
Complete all courses and trials in Tutorial.
Lose Buddy to the lava.
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.
Complete a Pogo trial.
Complete a Tiny Toy trial.
Build up boost to 5 m/s.
Complete all challenges for a single course.
Unlock your first character.
Unlock all courses in Tutorial.
Tweak something in the Options menu.
Die by Collision.
Complete the Intro.