[Updated high score]
[High score has been updated.]
The high score for Wonder Boy is 30,000. This can be mildly tricky if you try to do this legit, but there is a nice little trick with hidden bonuses that net you enough points to get 30,000 easily. First, set lives to 5 in the options. Speedrun through the first level while collecting as many fruits as you can, but make sure you don’t pick up the skateboard. Also, make sure you collect the statue at the end of the first level. You should be at around 20,000 points. If not, reset the game. Once you’re on the second level, you will coming a across a section with 3 snails in a row. Kill all the snails, and then shoot at the edge of the ground right before the water, and either bonus points or a health pack will appear. Then just keeping killing yourself and picking up the bonus points or health pack over and over again until you run out of lives. You should have enough points by then. See the image below for clarification on where to shoot the ground:
Thanks to Figma for discovering this strategy in the first place.