Here is the full list of all 15 Bryce's Movement Engine¹ achievements.
You've defeated your first custodian! Keep going, there's a few more!
You cleared out all of the goodies in a level... greedy!
You bounced on all of the baddies in a level... dominant!
You used a cheat code... flagrant!
You found nine lives in a level... cat-like!
You won the final boss like a boss!
You didn't fall for it, you defeated the true final boss!
She caught you, best be running!
You passed outside of the bounds and corrupted the game!
You cleverly checked the same place twice and corrupted yourself to the end of the ROM!
You stowed away into the secret cave!
Bry touched you and now things may have changed!
Bry left some rings, you took the bait!
You waited through every credit to listen to the entirety of The Best Song Ever Written!™
You broke wind as you fell into a top hat... sneaker!