At the Tomy logo, hold A + B + X + Y on Controller 2 until the title screen appears. It will be red instead of blue to confirm correct entry. Now press L + R + Start to access the sound test.
Do the aforementioned A + B + X + Y code, but now hold one of the following button combinations as the "Attacker or Defender" screen fades out to go to the corresponding level:
|2 (Tiamat Gorge)||R + Start|
|3 (Railway)||Y + Start|
|4 (Underground)||X + Start|
|5 (Climbing Cheesering Tower)||B + Start|
|6 (Inside Cheesering Tower)||A + Start|