Achievements do not pop if you don't start Steam client as admin user.

If you can't access Steam overlay in-game, you will not be rewarded with achievements.

If you have played and reached achievements goals but you have not been rewarded, start Steam then Ubinota both as admin user, enter your game profile and achievements will pop.

Some of them (world completing ones for example) should need you to play again any of the completed houses of selected world to pop.

Unmissable achievements
Achievements marked as [unmissable] are story-related ones. You will get all of them simply reaching endgame.

After endgame you still have access to the Worlds, so it's possible to 100% the game without starting a new game.

Win one "!" level
Unlocks when: you win your first ! house

Start again a level despite 5 failures
Unlocks when: you start for the 6th time the same level after failing it 5 times in a row. You have to wait the end-level menu and click "play again". Using "reload" button does not count.

Press the red button without painting anything
Unlocks when: you press the red button without painting anything for the first time. In some of the last levels this is mandatory to inspect hidden painted cubes.

Win a level with a least 5 seconds of suspense
Unlocks when: you win a level and you have to wait at least 5 seconds before end-level menu. Easy to achieve in levels based on green or red paint.

Turn the equivalent of 3 turn on the same level
Unlocks when: the game gives you the option to rotate 3D a level. Just move your mouse on every axe.

Win a level in less than 15 seconds
Unlocks when: you beat a level in less than 15 seconds. Just do it with the first level skipping the tutorial.

Paint 20 cubes
Unlocks when: you paint your 20th cube.

Paint 100 cubes
Unlocks when: you paint your 100th cube

Paint 300 cubes
Unlocks when: you paint your 300th cube

Suck up 10 paint doses
Unlocks when: you suck paint from a cube for the 10th time

Suck up 20 paint doses
Unlocks when: you suck paint from a cube for the 20th time

Suck up 100 paint doses
Unlocks when: you suck paint from a cube for the 100th time

Win a second level with the phantom paint
Unlocks when: you beat 2 levels using phantom paint. These levels occurs in World 7

Use 5 times the yellow paint
Unlocks when: you paint your 5th cube with yellow paint. Yellow paints is available from World 6 onwards

Win 2 levels with the green paint
Unlocks when: you beat 2 levels using green paint. These levels occurs in World 5

Manage to use the red paint
Unlocks when: you beat the red paint tutorial level in World 4.

Save all the houses. Full stop
Unlocks when: you paint all the houses of the game (Worlds 1,2,3,4,5,7)

Lose the first level
Unlocks when: you fail the very first level of the game

Paint the superintendant's domain
Unlocks when: the last normal house of World 1 has been painted

Use 2 paint at the same time
Unlocks when: you win the first level in which you can use 2 different paints

Very good recruit
Save all the non "!" houses of the superintendant's domain
Unlocks when: all the normal houses of World 1 have been painted

Save all the houses of the superintendant's domain, even the "!" ones
Unlocks when: all the normal and ! houses of World 1 have been painted

Win the last level of the first chapter holding 13 cyan paint doses in the tank.
Unlocks when: you complete the last level of world 1 with 13 paint doses in your tank.

Note: you have to manually edit a game file to try out this achievement, because with the last game update you are starting the level with 11 doses.
Follow this guide: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=586969494
How to beat it: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=677905788

Paint the sugar sky
Unlocks when: the last house of World 2 has been painted

Save all the non "!" houses of the sugar sky
Unlocks when: all the normal houses of World 2 have been painted

Save all the "!" houses of the sugar sky
Unlocks when: all the ! houses of World 2 have been unlocked and painted

Win the last level of the sugar sky with only 3 paint doses.
Unlocks when: you use only 3 paint doses to solve the last level of World 2
How to beat it: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=677905788

Find the cloudologist
Unlocks when: the last house of World 3 has been painted

Save all the non "!" houses of the night sky
Unlocks when: all the normal houses in World 3 have been painted

Save all the "!" houses of the night sky
Unlocks when: all the ! houses of World 3 have been painted

Win the last level of the night sky with only 13 doses.
Unlocks when: you win the last level of World 3 using 13 paint doses
How to beat it: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=677905788

Study black clouds
Unlocks when: the last house of World 3 has been painted

Save all the non "!" houses of the red sky
Unlocks when: all the normal houses of World 3 have been painted

Save all the "!" houses of the red sky
Unlocks when: all the ! houses of World 3 have been painted

Win the last level of the red sky with only 4 doses.
Unlocks when: you win the last level of World 4 using 4 paint doses
How to beat it: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=677905788

Catch the ghost
Unlocks when: the last normal house of World 5 has been painted

Save all the non "!" houses in front of the sky hole
Unlocks when: all the normal houses of World 5 have been painted

Save all the "!" houses in front of the sky hole
Unlocks when: all the ! houses of World 5 have been painted

Collect all the ingredients of the recipe
Unlocks when: the last normal level of World 6 has been solved

Collect all the non "!" ingredients of the yellow sky
Unlocks when: all the normal levels of World 6 have been solved

Collect every ingredients in the yellow sky, even the "!" ones
Unlocks when: all the levels of World 6 have been solved

Win the third level of the yellow sky with only 7 doses.
Unlocks when: you beat level 3 of World 6 using only 7 paint doses
How to beat it: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=677905788

Save the world
Unlocks when: you reach endgame. You don't need to solve every normal level in the previous Worlds to reach endgame, only the ones that unlock the path to the last one.

Save all the non "!" houses of the ghost sky
Unlocks when: all the normal houses of World 7 have been painted

Save all the "!" houses of the ghost sky
Unlocks when: all the ! houses of World 7 have been painted

Find and win the hardest level of Ubinota
Unlocks when: you unlock and win the level selected in this image (bottom-left)