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