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