To temporarily edit a level, enter one of the following codes at the Player Name screen. This is the same editor used by the development team, but the save feature has been disabled.

YTMHNPA - Training mission
YTMHNPB
YTMHNPC
YTMHNPD
YTMHNPE
YTMHNPF
YTMHNPG
YTMHNPH - Bonus level

The editor options screen has the following choices:

Save file (this option is disabled)
Paste (allows objects to be pasted)
Delete (allows objects to be cut)
Copy (allows objects to be copied)
Stack (allows objects to be stacked on one another)
Texture (allows an object's texture map to be changed)
Paste Node (allows a game "screen" to be pasted)
Copy Node (allows a game "screen" to be copied)
Edit Node Y (default value)
Quit (restarts the game)

While in an editor option, B cycles through actions, C executes the current selection, X allows the current level to be played, and P displays the editor option screen.