Here is the full list of all 33 Runner3 achievements.
Unlock EVERYTHING!
Bonk the Timbletot!
Defeat Machineland's Boss!
Get all your friends over for some GRILLINS!
Got 'em All!
Finish all 9 Impossible Levels!
Collect all the Narrator's Puppetshow Puppets!
Get all the Gildans!
Defeat the Jungle Ruins' Boss!
Go exploring in the Retro World. Maybe you'll find a cute secret?
Witness something creepy.
Defeat Spookyland's Bosses!
Defeat The Caves' Bosses!
Buy a bunch of new digs!
Buy a bunch of Capes!
Invite a friend to the BBQ!
Head off the Beaten Path...
Get a Special in each Standard Level in any World!
Defeat Foodland's Boss!
Get a Perfect in each Standard Level in any World!
Buy a bunch of Accessories!
Better out than in...
Checkpoints? Who needs 'em!
Make it to the end of an Impossible Level!
Collect all Golds and Gems and finish an Impossible Level!
Defeat The Great Outdoors' Boss!
Get a Perfect+!
Get a Special+ and a Perfect+ in any Level!
Get a Special!
Get a Special+!
Get a Special AND a Perfect in any one level!
Get a Special, a Perfect, and one Bullseye in any Level!
Get a Perfect!