Here is the full list of all 33 Runner3 achievements.
Got 'em All!
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!
Defeat The Caves' Bosses!
Bonk the Timbletot!
Defeat Machineland's Boss!
Get all your friends over for some GRILLINS!
Collect all the Narrator's Puppetshow Puppets!
Witness something creepy.
Defeat Spookyland's Bosses!
Defeat The Great Outdoors' Boss!
Buy a bunch of Accessories!
Buy a bunch of Capes!
Make it to the end of an Impossible Level!
Collect all Golds and Gems and finish an Impossible Level!
Checkpoints? Who needs 'em!
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!
Head off the Beaten Path...
Get a Special+!
Get a Special+ and a Perfect+ in any Level!
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+!
Finish all 9 Impossible Levels!
Better out than in...
Unlock EVERYTHING!