Type the codes in-game just like in Doom:

nbdeity – toggles god mode (can still take damage over 100 health)
nbdeathless – gives full health and armor
nbkeys – gives all keys
nbkfa – give full health, ammo, keys, and weapons
nbshooters – gives all weapons
nbullets – infinite ammo

nbff – doubles fire speed (this will stack!)
nbfastfingers – double current weapon fire rate (can be used multiple times for insane results!)
nbregularfingers – sets fire speed back to normal

nbfrog – increases jump height by .1 each time it’s typed
nbman – resets jump height to normal
nbgotta – toggles double movement speed (also affects some vertical motions such as jump pads)
nbwoohoo – toggles a janky slow motion mode (careful, this can break the game when you switch levels!)
nbspoder – toggles climbing powerup for 300 seconds
nbufo – toggles ability to jet up into the air by holding space bar
nbhot – toggles superhot mode for 300 seconds
nbponcho – toggles lava suit for 300 seconds
nbreflect – mirror mode (cannot be toggled off)