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