Side-scrolling 8-bit horror goodness.
The game is a 2-D sidescroller, which is what the old 8-bit system was best at. You'll need to navigate you way through 6 unique stages, but rather than just purely moving to the right you would also need to climb stairs and sometimes head to the left. Scattered throughout the game are tons of familiar horror enemies, like skeletons, hunchbacks, crows, knights and bats. There are also Greek mythological enemies like Medusa heads. Some can go down with one shot, but some can take a bit more damage.
Your main weapon throughout the game is the Belmont's signature whip, but you can also obtain secondary weapons as well, like holy water, axes, and a stop watch to stop time for a brief moment. These weapons are especially useful against the bosses. To obtain these items, as well as the ammunition needed to use them, you need to break candles. The ammunition in the game is hearts. It's weird at first, seeing as how most of the time hearts represent health and we don't normally think to break candles. But to longtime fans of the series, it's common. There are also a variety of other items, such as weapon power-ups, money, and special hidden crowns. The only thing you can do to replenish your health is to find a pork chop hidden somewhere behind a wall (again, people new to the series aren't going to realize that, or even find it either without luck or a guide).
If there's one thing the game is known for the most, it's the extreme difficulty. This is for a number of reasons: 1) Every time you get hit, you bounce back. If you are on the edge of a platform, you're pretty much dead. 2) The control feels pretty stiff. This can present a problem when trying to jump on platforms or dodge enemies. 3) Some of the enemies are just brutal. This specifically portrays to flying enemies like the Medusa heads and bouncing enemies like the hunchbacks. Enemies with projectiles can be a problem as well. The difficulty would be just fine if the enemies weren't always pushing you back.
For being an early game, Castlevania looks pretty damn awesome. It has a gritty and dark horror feel to it that stood itself apart from other games at the time. The environments and characters look great and the level design (while cheap in a couple of places) is strange, but good overall. Just as impressive is the music. All the tunes are incredibly catchy and memorable and most certainly set the feel for the game perfectly.
To sum things up:
-Impressive graphics with a nice horror feel to it
-Kick ass music
-With experience, the difficulty shouldn't be too big of a problem
-Cool-looking enemies and environments
-Cheap flying and bouncing enemies
-When you get hit, you bounce back, which makes it frustrating near platforms
-Controls feel a bit stiff
Flaws aside, this game is great. The Castlevania games were able to improve from this game over the years thanks to the SNES and Playstation, but I always like to go back to this game. It can be frustrating, but the feeling of being able to beat the game (which I have yet to do) will be extremely satisfying.