Full list of all 45 1 Square (Windows) achievements worth 3,000 gamerscore. It takes around 0-0.5 hours to unlock all of the achievements in the base game.
The base game contains 35 achievements worth 1,000 Gamerscore, and there are 2 DLC packs containing 10 achievements worth 2,000 Gamerscore.
Clear Level 1 - Normal Mode
Clear Level 2 - Normal Mode
Clear Level 3 - Normal Mode
Clear Level 4 - Normal Mode
Clear Level 5 - Normal Mode
Clear Level 6 - Normal Mode
Clear Level 7 - Normal Mode
Clear Level 8 - Normal Mode
Clear Level 9 - Normal Mode
Clear Level 10 - Normal Mode
Clear Level 11 - Normal Mode
Clear Level 12 - Normal Mode
Clear Level 13 - Normal Mode
Clear Level 14 - Normal Mode
Clear Level 15 - Normal Mode
Clear Level 16 - Normal Mode
Clear Level 17 - Normal Mode
Clear Level 18 - Normal Mode
Clear Level 19 - Normal Mode
Clear Level 20 - Normal Mode
Clear Level 21 - Normal Mode
Clear Level 22 - Normal Mode
Clear Level 23 - Normal Mode
Clear Level 24 - Normal Mode
Clear Level 25 - Normal Mode
Clear Level 26 - Normal Mode
Clear Level 27 - Normal Mode
Clear Level 28 - Normal Mode
Clear Level 29 - Normal Mode
Clear Level 30 - Normal Mode
Clear Level 31 - Normal Mode
Clear Level 32 - Normal Mode
Clear Level 33 - Normal Mode
Clear Level 34 - Normal Mode
Clear Level 35 - Normal Mode
Clear Level 16 - No Flooding Mode
Clear Level 17 - No Flooding Mode
Clear Level 18 - No Flooding Mode
Clear Level 19 - No Flooding Mode
Clear Level 20 - No Flooding Mode
Clear Level 21 - No Flooding Mode
Clear Level 22 - No Flooding Mode
Clear Level 23 - No Flooding Mode
Clear Level 24 - No Flooding Mode
Clear Level 25 - No Flooding Mode