Here is the full list of all 100 Mosaique Neko Waifus 2 achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
SOLVE 40 PUZZLES
SOLVE ALL CHEN AND SUYIN PUZZLE
COLLECT 40 ITEMS
ALL GIRLS JUMP OUT OF THEIR CLOTHES
SOLVE FIRST CHEN AND SUYIN PUZZLE
SOLVE ALL SARA AND SAYOURI PUZZLES
SOLVE 35 PUZZLES
FINISH SARA AND SAYOURI EXTRA PUZZLE
COLLECT 35 ITEMS
SOLVE FIRST SARA AND SAYOURI PUZZLE
SOLVE 30 PUZZLES
COLLECT 30 ITEMS
SOLVE ALL CHEN PUZZLES
FIRE "EARTHQUAKE" 10 TIMES
SOLVE FIRST CHEN PUZZLE
SOLVE 25 PUZZLES
COLLECT 25 ITEMS
VIEW 100 PHOTOS
VIEW 2 PHOTOS
VIEW 1 PHOTO
SOLVE ALL SAYOURI PUZZLES
CLICK A PIECE WITH "SECRET PRESENT" 5 TIMES
SOLVE 1000 BLOCKS
SOLVE 900 BLOCKS
SOLVE 20 PUZZLES
SOLVE 800 BLOCKS
GAIN 30000 EXPERIENCE
COLLECT 20 ITEMS
SOLVE FIRST SAYOURI PUZZLE
SOLVE 700 BLOCKS
SOLVE ALL NIKO PUZZLES
LEVEL UP TO LEVEL 30
CLICK A PIECE WITH "SECRET PRESENT"
UNLOCKED "FLASH BOMB" IN SKILL TREE
SOLVE 15 PUZZLES
SOLVE 600 BLOCKS
"LOVE SPARKLE" FIRED 50 TIMES
LEVEL UP TO LEVEL 25
UNLOCKED "SECRET PRESENT" IN SKI
COLLECT 15 ITEMS
SOLVE 500 BLOCKS
LEVELED 20 ABILITIES IN TOTAL
CLICK THE PUZZLE PIECES 1000 TIMES
LEVEL UP TO LEVEL 20
FIRE "CHOCOLATE AIRSTRIKE" 30 TIMES
CLICK THE PUZZLE PIECES 900 TIMES
SOLVE 400 BLOCKS
SOLVE 20 PIECES USING "FLIP ALMOST SOLVED"
CLICK THE PUZZLE PIECES 800 TIMES
LEVELED 15 ABILITIES IN TOTAL
GAIN 10000 EXPERIENCE
FINISH NIKO EXTRA PUZZLE
LEVEL UP TO LEVEL 15
SOLVE 300 BLOCKS
CLICK THE PUZZLE PIECES 700 TIMES
SOLVE 10 PUZZLES
"FLARE" FIRED 15 TIMES
COLLECT 10 ITEMS
SOLVE FIRST NIKO PUZZLE
CLICK THE PUZZLE PIECES 600 TIMES
UNLOCKED "LOVE SPARKLE" IN SKILL TREE
UNLOCKED "EARTHQUAKE" IN SKILL TREE
UNLOCKED "CHOCOLATE AIRSTRIKE" IN SKILL TREE
UNLOCKED "FLIP ALMOST SOLVED" IN SKILL TREE
UNLOCKED "PEEK" IN SKILL TREE
UNLOCKED "FLARE" IN SKILL TREE
SOLVE ALL SARA PUZZLES
SOLVE 200 BLOCKS
"LOVE SPARKLE" FIRED 10 TIMES
LEVELED 10 ABILITIES IN TOTAL
GAIN 5000 EXPERIENCE
CLICK THE PUZZLE PIECES 500 TIMES
LEVEL UP TO LEVEL 10
CLICK THE PUZZLE PIECES 400 TIMES
CLICK THE PUZZLE PIECES 300 TIMES
SOLVE 100 BLOCKS
SOLVE 5 PUZZLES
GATHER 7 UNSPENT ABILITY POINTS
CLICK THE PUZZLE PIECES 200 TIMES
SOLVE 50 BLOCKS
CLICK THE PUZZLE PIECES 100 TIMES
COLLECT 4 ITEMS
COLLECT 5 ITEMS
GATHER 5 UNSPENT ABILITY POINTS
LEVELED 5 ABILITIES IN TOTAL
COLLECT 3 ITEMS
LEVEL UP TO LEVEL 5
CLICK THE PUZZLE PIECES 50 TIMES
COLLECT 2 ITEMS
SOLVE 2 PUZZLES
SOLVE 10 BLOCKS
COLLECT 1 ITEM
SOLVE FIRST PUZZLE WITH SARA
GATHER 2 UNSPENT ABILITY POINTS
SOLVE 1 PUZZLE
CLICK THE PUZZLE PIECES 10 TIMES
LEVEL UP TO LEVEL 2
SOLVE 1 BLOCK
CLICK THE PUZZLE PIECES FOR THE FIRST TIME
HELLO THERE!