Here's a list of secret commands you can use in gunbound.
Only one of them does anything really neat. The rest give a
special message from the game's Korean programmers (so if you
can't read Korean, you're out of luck, although some of it
is in english). There used to be a /worldcup code that
allowed you to shoot little soccerballs and have a special
soccer background, but it was removed :(

/cjswoshrdua (activates christmas background)
/gunbound (deactivates christmas background - Credit to MisFate )