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