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