Mario & Wario

Yes, it's that game with Mario and a bucket.

Debug mode
The PAR code enables a few debugging buttons on Controller 2. Press any of these during gameplay:
 * X: go to the "Hit Wario" bonus game
 * Select: view the ending and credits
 * Pressing either of these two at the title screen will stop the music, but nothing else.
 * Start: access the level select and sound test
 * Pressing this at the title screen does the same thing, but only the sound test will work correctly.