Heavy Unit — Cheat codes

At the title screen, hold A + B + C and press Start to access a series of test menus where you can view the various graphics used in the game.

Enter these in the options screen

99 credits    TOMOYO
Change in-game colors    COLORB
Change in-game colors    COLORC
Change in-game colors    COLORD
Change in-game colors    COLORE
Change in-game colors    COLORF
Change in-game colors (restore default value)    COLORA
DEMO-REC mode    OGOSHI
Invert colors    INVERT
Invincible    OHNUKI
Record gameplay    RECORD
Replays recorded gameplay    REPLAY
Stage progress counter    LOCATE
Stage select    SOSITE

Secrets:
To display a hidden credits text string, highlight Password in the options screen and press B 100 times.