Here is the full list of all 34 Runner3 trophies - there are 20 bronze, 7 silver, 6 gold and 1 platinum.
Get all the Gildans!
Defeat the final boss of the Retro Game!
Collect all Golds and Gems and finish an Impossible Level with a Score Multiplier of 100% or more!
Go exploring in the Retro World. Maybe you'll find a cute secret? (You will.)
Defeat the Widow Sisters boss in The Caves!
Collect all the Narrator's Puppetshow Puppets!
Checkpoints? Who needs 'em!? You don't! Clear a level after jumping over the checkpoint.
Get all your friends over for some GRILLINS!
Bonk the Timbletot!
Reverse Merman; may you rest... In pieces? Defeat Reverse Mermech!
A coin collector's dream come true! Get all the Character Coins!
Witness something creepy (other than Unkle Dill). Some things are not as they seem...
Head off the Beaten Path...and find something!
Leaf Scarickson? More like Leaf Whereickson! Defeat the Great Outdoors Boss!
Make it to the end of an Impossible Level with a Score Multiplier of 100% or more!
Better out than in...
Owl outta time! Defeat the Fat Lords in the Parliament of Owls!
Buy a bunch of new digs! Fill up that closet!
Get a Special in each Standard Level in any World!
Get a Perfect in each Standard Level in any World!
Buy a bunch of Capes! It's like a superhero convention exploded in here!
Buy a bunch of Accessories! Get all gussied up!
Invite a friend to the BBQ!
You're a Wiener! Defeat The Sausage Santa!
Get a Special+ and a Perfect+ in any Level!
Hit the Bullseye after getting a Perfect in any Level!
Hit the Bullseye after getting a Special in any Level!
Get a Special, a Perfect, and one Bullseye in any Level!
Get a Special!
Get both a Special AND a Perfect in any Level!
Got a Perfect!
Get all other Trophies and this one's yours!
Finish all 9 Impossible Levels with a Score Multiplier of 100% or more!
Unlock EVERYTHING! Yes, even that thing.