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