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