Here is the full list of all 20 Slender: The Arrival trophies - there are 19 bronze and 1 silver.
Beat the game on "Hardcore" difficulty
Die in the 'Into the Abyss' level 3 times in a row
Beat the Genesis level on "Hardcore" difficulty
Get ensnared by Slender Man’s tenticles
Find all scrapbook items
Beat 'The Eight Pages' level in under 5 minutes
Beat the game in under 45 minutes
Disrupt Charlie while he's crying at least 3 times
Beat the game on normal difficulty
Make it through the forest fire without catching on fire once
Find all numbered letters
Surpass 10 000 total steps taken
Beat the 'Into The Abyss' level in under 5 minutes
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Exceed 50 failed pause attempts
Exceed 10 failed pause attempts
Pick up an oversized sign and somehow manage to fit it in your scrapbook
Play the piano until the first notes from "No Friends" is played
Listen to all of the radio tracks in the house
Riding a Slide in a Horror Game