Here is the full list of all 50 Sylvio achievements.
Found arcade game no. 1
Found arcade game no. 2
Found arcade game no. 3
Found arcade game no. 4
Found one hidden message
Found 10 hidden messages
Found 25 hidden messages
Found 60 hidden messages
Found 100 hidden messages
Found all hidden messages
Found all shreds of piano sheet one.
Found all shreds of piano sheet two.
Found all shreds of piano sheet three.
Found all shreds of piano sheet four.
Found all shreds of piano sheet five.
Notes from the static : 1 found
Notes from the static : 10 found
Notes from the static : 20 found
Notes from the static : 40 found
Notes from the static : 60 found
Notes from the static : All found
Played the piano in the auditorium.
Used the entertainment system in the restaurant.
Blinked a hidden combination on the signal lamp.
Blinked a combination, and the pump started.
Shot the crow by the hotel rides.
Looks like an exhibition of cave paintings.
Retrieved the hotel key from corpse hanging from giant balloon.
All notes and recordings found in the cellar.
All notes and recordings found in the surroundings of the ice cream hut.
All notes and recordings found in the surroundings of the big house.
All notes and recordings found in the surroundings of the funfair.
All notes and recordings found in the surroundings of the hotel.
All notes and recordings found in the surroundings of the zoo.
Communicated with Daniel in the cellar.
Communicated with unknown by the ice cream hut.
Communicated with Kristoph in the trailer by the big house.
Communicated with Susie on the funfair.
Communicated with Roger's lover in the hotel bathroom.
Communicated with guard at the zoo entrance.
Communicated with Robin in various places of Saginaw main park.
Found all of Bobby's reels.
Game finished with all piano sheets complete.
All notes and recordings found in the main park of Saginaw.