To access the game's debug mode, open the option menu from the title screen. Once there, input the following:

Down, Down, Left, Up, Down, Right, Up, Up, 1, 2, 1, Down, Down, Down, Down

The game is very lenient in terms of time, so it's better to make sure the sequence is correct as opposed to rushing through it. When completed, the number of options available will greatly expand, allowing access to the title's debug mode. If done incorrectly, the player will have to exit options and then re-enter before attempting again.

Debug Options
Control Test -
This option lets the player toggle which, if any, of the forces they will be playing in the game. This mode allows for Gigan, King Ghidorah and SpaceGodzilla to be controlled on the map, although actual fighting is done entirely by the game's AI with these units. This mode also allows the player to access the game's fifth stage instantly, if "right and start" are held just before the stage selection appears.
Pattern Test -
This selection allows the player to cycle through all of the characters, along with seeing each individual sprite created for them, while the background can also be changed to any stage available in the game. The player can press start at any time to return to the debug menu.
Versus Test -
The Versus Test allows the player access to the game's fighting engine, removed from the map component of play. The player can select their" character, opponent, the background, toggle the timer and even have two CPUs fight one another. This mode includes every character in the game, including all of the G-Force units and the previously unplayable characters like SpaceGodzilla. Matches can be exited by pressing start at any time.
Ending Test -
Not much to this option, which just allows the player to see the title's ending sequence. The ending shown is the one for G-Force, and Godzilla's does not appear to be accessible. Once started, the player will have to wait until all of the credits roll before the game will return to the main menu and the debug mode will have to be enabled again.
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