Castlevania/Secrets

Bonuses
Throughout the castle, there are several special bonuses including money bags (1000 points) and crowns/treasures (2000 points). These nearly impossible to find bonuses are revealed by crouching or standing on appropriate blocks.

The second quest has a few more secrets which can be seen in this video:.

Pot Roasts
Life restoring Pot Roasts can be found by destroying certain blocks throughout the castle. Each Roast restores six bars of health, so finding one can easily be the difference between life and death.

Shot Multipliers
Shot Multipliers allow you to have two or three special weapons on screen at once, which lets you kill things, especially the bosses much more quickly. Multipliers can be dropped by enemies or candles, but also found in certain blocks.

Second Quest
After you beat Dracula and the game one time, you can continue after the credits roll. You will begin back at Stage 1 with any special weapon that you had the last time, but the game will be much more difficult. Every time that you get hit, you will sustain four units of damage, so you can only be hit four times before dying. The enemies also come in larger numbers and move significantly faster, though they don't take any additional hits to kill.

Additional changes:
 * Stages 1 - 3: In all above grounds sections, Bats will be constantly flying about, often at the most inconveniently height possible. Fishmen and Ghouls will also appear in much greater numbers.
 * Stages 4 - 6: All three stages are now populated with Medusa Heads. The spikes in Stage 6 now pose one of the greatest challenges of the game since you have to try and time your movements while avoiding the Heads.
 * Stages 10 - 11: Many, many more Bats than before, and they now appear along side the Eagle/Fleaman teams (which also appear in greater numbers). The Fishmen are much more numerous in the underground river and may jump up directly below you.