Various

Play as Enzo
At the main menu, press Up, Left, Down, Left, Down, L1, R1, Right, Down, Right, then start a new game.

Play as Dot
At the main menu press Left, R1, Right, Up, Down, R2, L1, Right, Up, Down

Flying
At the main menu, press Left, Down, Right, Left, Up, R2, L1, Up, Left, Right.

Free Shield with Every Glitch Pickup
At the main menu press Down, R1, Left, Right, Down, L2, R2, Left, Right, Up.

Full Glitch Energy
At the main menu press Right, L1, Up, Right, Down, L1, R1, Up, Down, Left.

Max Out All Weapons At the main menu press Up, L1, Down, Up, Left, R1, L2, Down, Left, Right.