Wonderboy

Unlimited lives:
Press C at the title screen.

Unlimited lives (alternate):
Load or reset the game, then execute the following BASIC commands before running or restarting the program.

POKE 2676,234
POKE 2677,234
POKE 2678,234
SYS 2112

Unlimited lives (alternate):
Load or reset the game, then execute the following BASIC commands before running or restarting the program.

POKE 2676,238
SYS 2112

Level select:
Load or reset the game, then execute the following BASIC commands before running or restarting the program. Note: X represents the desired level.

POKE 2391,X
SYS 2112

Unlimited health:
Load or reset the game, then execute the following BASIC commands before running or restarting the program.

POKE 11760,165
POKE 62379,165
POKE 62401,165
POKE 62728,165