Here is the full list of all 61 Hidden Cats in Berlin achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
You Found 5 Cats
You Found 10 Cats
You Found 15 Cats
You Found 20 Cats
You Found 25 Cats
You Found 30 Cats
You Found 35 Cats
You Found 40 Cats
You Found 45 Cats
You Found 50 Cats
You Found 55 Cats
You Found 60 Cats
You Found 65 Cats
You Found 70 Cats
You Found 75 Cats
You Found 80 Cats
You Found 85 Cats
You Found 90 Cats
You Found 95 Cats
You Found 100 Cats
You Found 110 Cats
You Found 150 Cats
You Found 200 Cats
You Found 250 Cats
You Found 300 Cats
You Found 400 Cats
You Found 500 Cats
You Found 600 Cats
You Found 700 Cats
You Found 800 Cats
Found All Cats Normal
Found All Cats Advanced
You Found Einstein's Cat
You Found Wurst Cat
You Found Grumpy Cat
You Found Gothic Punk Cat
You Found Goethe's Cat
You Found Bethoven's Cat
You Found Irena
You Found Luke
You Found Darvin
You Found Capuccino
You Found Clóvis
You Found Bichin
Backerei Completed
Berlin Wall Completed
Brauhaus Completed
Hauptbahnhof Completed
Metzgerei Completed
Tiergartent Completed
The Underground Party Completed
Berlin Tiergarten Discovered
Brandenburg Gate Discovered
Pergamon Museum Discovered
TV Tower Discovered
Postdamn Platz Discovered
Berlin Wall Discovered
Oberbaumbrucke Discovered
Hauptbanhoff Discovered
Finish with no Hints Normal
Finish with no Hints Advanced