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