- You get extra men at 20000 points and again at 50000 points. I think at every 50000 after that, too.
- You can use the whip to hit many enemies, like the big one pictured here, almost indefinitely. The trick is to let him recover from his recoil after each hit. They just don't die. This gets you 300 points for each hit. After enough hits, you can hit him twice to put him down for good, if you need to.
- If you exploit the game this way, you can get 4500 points in 10 seconds of game clock. When you've got over 20 seconds, you can easily get 10000 points for a modest amount of work.
Yep, once you start looking for them, a good number of games have exploits like this.
You can make Castlevania a fair bit easier if you manage to get and keep the holy water or boomerang early on, and use it to defeat multiple enemies with a single shot. The second kill is worth an extra 1,000 points, the third 2,000, the fourth 4,000 and after that you either earn no addition bonuses (GBA port) or glitched scores (NES version) that tend to be worth even larger numbers of points.
You earn your first extra life at 30,000 points, and then every 50,000 after that. The first and third stages of the first "block" have sections where zombies appear indefinitely. Each kill is only 100 points by itself, but if you use the holy water located atop the staircase in the first of these areas, you can easily take out three zombies per use, and occaisionally four or even five. It is not hard to get around 50,000 points or more doing this, enough for one extra life and a good start on a second, and still have enough time to finish off the boss. The bone statues found later in the game can also be exploted for a quick thousand by destroying the fireballs they shoot, and the indestructable red skeletons can also be thus taken advantage of when they appear in groups.