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