Here is the full list of all 100 Hentai Unlimited achievements.
Complete another puzzle
Complete 8 puzzles from a fifth artist
Collect 50 bronze medals
Complete 5 puzzles from a fifth artist
Complete 8 puzzles from a fourth artist
Collect 30 silver medals
Collect 30 bronze medals
Complete 100 puzzles
Complete 8 puzzles from a third artist
Complete 5 puzzles from a fourth artist
Complete 90 puzzles
Complete 2 puzzles from a fifth artist
Collect 25 gold medals
Complete 5 puzzles from a third artist
Complete 80 puzzles
Collect 20 gold medals
Collect 20 silver medals
Complete 70 puzzles
Complete 2 puzzles from a fourth artist
Collect 15 gold medals
Collect 15 bronze medals
Complete 60 puzzles
Complete 8 puzzles from a second artist
Complete 50 puzzles
Collect 10 silver medals
Collect 10 gold medals
Complete 40 puzzles
Complete 2 puzzles from a third artist
Complete 5 puzzles from a second artist
Complete 30 puzzles
Complete 2 puzzles from a second artist
Complete 8 puzzles from the same artist
Complete 20 puzzles
Complete 5 puzzles from the same artist
Complete 10 puzzles
Complete 2 puzzles from the same artist
Complete one puzzle