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