Castlevania 64 Unlockables & Cheat Codes

Unlimited Money
Defeat the bull in the Castle Center, then return to the white crystal save point. Locate and open the large crate to collect $2000. Save and load the game and open the crate again. Repeat this action to gain an unlimited amount of money.

Alternate Costumes
Complete the game with either character, after you have gotten the two crystals from the Towers.

As Reinhardt, go to the third level in the Tower of Execution, and break open an iron maiden to find an execution key. Return back down to the second level and open the gate with the key. Walk through the hallway and look over the edge to find a floating platform with another iron maiden on it. Jump down to it and break the iron maiden to get the purple jewel for his Second Secret.

As Carrie, head to the top of the Tower of Sorcery and find a floating platform with a torch on it. Put holy water on it then hit the torch to find the purple jewel for her Second Secret.

After that, save the game and then, holding the Analog Stick Up, highlight the character that was used to beat the game. Select the character to get their alternative costumes. Reinhardt's costume is the same as Simon Belmont's costume, and Carrie's costume is a school girl outfit.

Charlie Vincent Ending Sequence
Use more than four cards during game play and you will get a battle with Charlie Vincent at the end of the game.

Fight Renon
If you spend over 30,000 on buying stuff from the devilish salesdemon Renon, he will attack you.

Access Hard Mode
When in the Forest of Silence, walk along the invisible ramp to the inaccessible platform over one of the ravines to find a torch. Break it open with your primary weapon to collect the Special1 jewel, then when you beat the game and save, you'll have access to the Hard Mode. You must, however, collect the Special1 jewel for this to work.

Save in the Duel Tower
There are no save crystals in the Duel Tower, but there is a secret to save your game. Simply beat one of the bosses in the Tower, and then return to the Castle Center. Save your game at the elevator. This way you won't have to keep fighting the same bosses over and over again in the Duel Tower if you die.