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