Here is the full list of all 120 Geometry Dash achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Complete "Time Machine" in Normal mode
Complete "Cycles" in Normal mode
Complete "Clutterfunk" in Normal mode
Complete "Electroman Adventures" in Normal mode
Complete "Clubstep" in Normal mode
Complete "Electrodynamix" in Normal mode
Complete "Hexagon Force" in Normal mode
Complete "Theory of Everything 2" in Practice mode
Complete "Theory of Everything 2" in Normal mode
Complete a Demon difficulty level in Normal mode
Complete 2 Demon difficulty levels in Normal mode
Complete 3 Demon difficulty levels in Normal mode
Complete 4 Demon difficulty levels in Normal mode
Complete 5 Demon difficulty levels in Normal mode
Complete 10 Demon difficulty levels in Normal mode
Complete 15 Demon difficulty levels in Normal mode
Complete 20 Demon difficulty levels in Normal mode
Complete 30 Demon difficulty levels in Normal mode
Complete 40 Demon difficulty levels in Normal mode
Collect 100 stars
Collect 200 stars
Collect 300 stars
Collect 400 stars
Collect 500 stars
Collect 600 stars
Collect 700 stars
Collect 800 stars
Collect 900 stars
Collect 1000 stars
Collect 1500 stars
Collect 2000 stars
Collect 25 Secret Coins
Collect 30 Secret Coins
Collect 35 Secret Coins
Collect 40 Secret Coins
Collect 45 Secret Coins
Collect 50 Secret Coins
Collect 55 Secret Coins
Collect 60 Secret Coins
Collect 65 Secret Coins
Collect 70 Secret Coins
Collect 75 Secret Coins
Collect 80 Secret Coins
Collect 85 Secret Coins
Collect 90 Secret Coins
Collect 95 Secret Coins
Collect 100 Secret Coins
Complete 5 Map Packs
Complete 10 Map Packs
Complete 15 Map Packs
Complete 20 Map Packs
Complete 25 Map Packs
Complete 30 Map Packs
Complete 200 user created levels in Normal mode
Complete 300 user created levels in Normal mode
Complete 500 user created levels in Normal mode
Complete 1000 user created levels in Normal mode
Like or Dislike 1000 online levels
Rate the difficulty of 1000 online levels
Get 100 likes on a created level
A secret is required
Complete "Clubstep" in Normal mode (Steam Exclusive Bonus)
Complete 100 user created levels in Normal mode
Rate the difficulty of 100 online levels
Complete "Clutterfunk" in Practice mode
Complete "Theory of Everything" in Practice mode
Complete "Theory of Everything" in Normal mode
Complete "Electroman Adventures" in Practice mode
Complete "Clubstep" in Practice mode
Complete "Electrodynamix" in Practice mode
Complete "Hexagon Force" in Practice mode
Complete "Blast Processing" in Practice mode
Do 10000 attempts
Jump 50000 times
Complete "Cycles" in Practice mode
Complete "xStep" in Practice mode
Complete a Map Pack
Complete 50 user created levels in Normal mode
Like or Dislike 100 online levels
A hidden treasure is required
Review "Geometry Dash" and let us know what you think
Complete "Time Machine" in Practice mode
Collect 20 Secret Coins
Complete "Jumper" in Practice mode
Complete "Cant Let Go" in Practice mode
Collect 15 Secret Coins
Complete "Base After Base" in Practice mode
Complete "Dry Out" in Practice mode
Subscribe to RobTop Games on YouTube
Complete "Blast Processing" in Normal mode
Complete "xStep" in Normal mode
Like Geometry Dash on Facebook
Complete "Polargeist" in Practice mode
Complete "Back On Track" in Practice mode
Complete "Stereo Madness" in Practice mode
Do 2000 attempts
Create and submit a custom level
Jump 20000 times
Complete "Cant Let Go" in Normal mode
Complete "Jumper" in Normal mode
Jump 10000 times
Complete "Base After Base" in Normal mode
Collect 10 Secret Coins
Click on the More Games button!
Crash at over 95% on a main level in normal mode
Complete "Dry Out" in Normal mode
Complete level 1-3 in Normal mode (Steam Exclusive)
Complete "Polargeist" in Normal mode
Collect 5 Secret Coins
Complete "Back On Track" in Normal mode
Complete "Stereo Madness" in Normal mode
Do 500 attempts
Complete 10 user created levels in Normal mode
Jump 1000 times
Do 100 attempts
Like an online level
Rate the difficulty of an online level
Complete a user created level in Normal mode