Puyo Puyo (NES)
The exact same as the Famicom Disk System version, but with worse music and visuals. Yay.
At the main menu, hold Up + A + B then press Start. Use the D-Pad to select a sound.
Unused Game Mode
The Game Genie code EAENEYAA re-enables a disabled game mode cheat. Hold Up + A + B + Select + Start, then press Reset. The title screen will change color and the two player mode, limits 42 and 60 will be changed to 50 and 80.
Unused Extra Password
At the password screen, select the fourth password character to edit (do not change the first three!), select a letter, hold Select and press A or Start. To the right of the password a new string ended with "0" will appear. Every time you press A or Start while holding Select at this position, a new letter will be added to this string. You can't return and change previously entered symbols, there are 8 symbols total to enter. When finished, enter the last three characters of the password as usual with the check code (do not change the "?" in the first one!). Now, hold Select and press A or Start. The program will compare the sum of the particular chars in 8-symbol string you entered with check code in place of the password and if they match will display the "PASSWORD OK!" message. However, there is no purpose in this string here at all in the final version of the program. To test this, just enter the secret pass "00000000" as described above, then enter the check code "?000" instead of the password.