Defeat Death in Stage 5, then go to Alternate Stage 4 and defeat Camilla.
Dracula X: Rondo Of Blood: Play as Maria
When the minotaur chases Richter in Stage 2, get the Key subweapon from the candlestick. Go down into the sewers after the minotaur gets blocked by the wall. Use the Key subweapon on the locked door at end of the sewer. This will trigger an intermission sequence showing Maria joining Richter. She can now be selected as a playable character at the main menu.
Dracula X: Rondo Of Blood: Unlock Castlevania: Symphony Of The Night
When the minotaur chases Richter in Stage 2, immediately fall into the first hole to enter the sewers. Complete the level as usual by defeating the Boss. You will then start Stage 3', the alternate version of Stage 3. Every time your path splits in Stage 3', always select the upper route. Collect the Axe subweapon when it becomes available. Use it to cut the vine-covered cage near the skeletal snake that is attached to a wall. Jump on the cage to allow Richter to jump to the upper ledges. Continue along the upper ledges until reach a breakable tombstone that contains the item that unlocks Castlevania: Symphony Of The Night as a playable game at the main menu.
How to Save Iris
She's found in Alternate Stage 4. Simply keep going through the stage (do not go down the waterfall on the raft yet). Go all the way across this part of the stage until you notice a blue frog. Don't kill it. Instead jump over/avoid it and let it stay close. It will follow to the end of this particular part of the stage to a row of frog statues. It will jump on the only pillar that doesn't have a frong statue on it and lower a plateform in the middle of this section of the stage. Go down the stairs and follow the path until you get to the end where there is a gate. Iris is awaiting there.
How To Save Tera
She's found in Alternate Stage 3: Go through the stage until you get to the very end of the first half. You'll see your first door and a small plateform underneath that appears to be a dead end. Simply jump under the door and hit the wall, from the top to the bottom. Go down the stairs there and you'll save Tera.
Keep your inventory at the beginning of the game (Symphony of the Night)
In order to keep your default inventory at the beginning of the game, like the Alucard Sword and Alucard Shield, reach the room where you meet Death for the first time, then walk back out or back dash out of the room. If done correctly, Death won't be there when you re-enter the room. Note: this glitch works differently from the original PS1 version.
Level Select code for Origional Rondo of Blood
Enter this code as your player name in the Origional Rondo of Blood game to unlock the Level Select option on the menu and skip to any Level in the game. Just like the symphony of the night Luck code, this is where it all started.
Password
Effect
X-X!V''Q
Level Select for Rondo of Blood
New Modes in Symphony of the Night
After clearing the game as Alucard for the first time, you can start special modes by entering a specific name when you select a new game.
Password
Effect
MARIA
Play as Maria Renard
RICHTER
Play as Richter Belmont
X-X!V''Q
Play as Alucard, with 99 luck and the Lapis lazuli (+20 luck) accessory
AXEARMOR
Play as Alucard, with the Axe Lord armor
DEATH
Death will not steal your weapons and armor in the early cutscene.
Original Game
Using Maria in stage two, fall down the first pit when the behemoth is chasing you and beat the rest of the level. You will then be taken to a secret stage three. Eventually, you will come to a point that has two paths. Take the upper path and continue along. You will soon come to a point that has platforms on the top and bottom. Break the vine at the top and continue to jump on the top platforms. Break the tombstone at the end and you can play the original version of Rondo of Blood!
Play as Maria (Rondo of Blood)
In Stage 2, while the Behemoth is chasing Richter, there is a candlestick that contains the "key" subweapon. Make sure to get it, and then proceed down into the sewers after the Behemoth is blocked by the wall. At the very end of the sewer path, there is a locked door. Use the key subweapon and it will unlock, giving you a cinematic scene where Maria joins Richter. She is now selectable as a playable character in the main menu.
Richter's secret long whip attack
Richter's whip can be extended secretly! If you press forward two times just after pressing the attack button, Richter's whip will extend slightly, making it easier to hit some enemies. You'll know it works when the whip turns white during the animation. It can also be done while jumping and crouching, you just have to hold the crouch button while pressing forward two times.
Rondo of Blood: Stage Select
To select any stage without the work, enter X-X!V''Q as your name.
Saving Annette
Annette is located in Stage 7. You first need to rescue Terra and Iris to be able to do this.
In the first room of the clock tower section, break the red pillar statue and push the switch behind it. Next, climb to the top where there's a small cog wheel and locked door in the upper right corner. Hit the cog wheel until the door opens and enter that. In this next area, kill the hawk to obtain the key. Hold on to it for now.
Next, in the last room of the clock tower section, you'll see a locked door. DO NOT USE THE KEY here (as its a fake room) and instead proceed upward until you see a crystal pillar blocking another switch. Like before, break the pillar to push the switch. Now go back down to where the locked door is. If done correctly, a new area should have opened up below with another locked door below the first one. Open the new/lowest locked door and after a cutscene, you'll save Annette.
You can come back here again in later playthroughs to find a room with several candles that drop moneybags and the Stopwatch subweapon if you're using Richter.
The Stairs' Shaft
If you're looking for a useful tip to get through the game easily, consider the following glitch. This glitch allows you to pass through walls, floors, across pits, and more. You can basically bypass almost everything once you fall through the floor. Useful to get through some tough areas full of annoying monsters, to obtain some items not possible early in the game and/or to obtain others easily. In order to accomplish this glitch successfully, you must first head to any staircase. Climb up to the middle of the stairs and stop. Then, walk back down to the lowest step.
From here, press down, and then quickly press backwards (pressing both simultaneously). If done properly, the character will have a foot on the stairs and another foot in or underneath or behind the floor you're trying to breach (that the stairs are connected to). When you see this, release back on the d-pad, and the character will fall completely through the floor to a glitched area underneath the stage.
If the glitch doesn't work, make sure of two things: that your character isn't facing the staircase, and that you're pressing down and backwards simultaneously. Also keep in mind that depending on where you are, the glitch may not work properly. You may get stuck and have to reset the game in certain areas. Maria is also preferable to Richter because she can jump higher and hence get out of these glitched areas more easily.
Unlock Original Dracula X game
Go to stage 4. On your way through twards the end of the stage you will find 6 of those skulls that spit fire stacked on top of each other. Just past them is a platform that moves like an inverted pengelium going left and right. Just opposite of it is a spiked ball. Get on the platform and jump over the spiked ball landing on the ground against the wall. Break the lower part of the wall to find a bomb. Hit the bomb to ingite it and the wall will come falling down. Walk forward a bit and you will find 2 spiked platforms that try to crush you. Get on the right platform and as it's going up jump off of it and land on the upper level. Stay on top avoiding the axes and the yellow eye. At the very end of that platform is a candle hit it and inside will be some classic gaming goodness.
Unlock Original Rondo of Blood game
Go to stage 4. On your way through twards the end of the stage you will find 6 of those skulls that spit fire stacked on top of each other. Just past them is a platform that moves like an inverted pengelium going left and right. Just opposite of it is a spiked ball. Get on the platform and jump over the spiked ball landing on the ground against the wall. Break the lower part of the wall to find a bomb. Hit the bomb to ingite it and the wall will come falling down. Walk forward a bit and you will find 2 spiked platforms that try to crush you. Get on the right platform and as it's going up jump off of it and land on the upper level. Stay on top avoiding the axes and the yellow eye. At the very end of that platform is a candle hit it and inside will be some classic gaming goodness.
Unlock Symphony of the Night
In Stage 2, while the minotaur is chasing Richter, immediately fall into the first hole in the ground. You will not die, but instead be taken into the sewers. Play the level out normally and defeat the boss. Afterwards, you will be taken to Stage 3' (this is different from the normal Stage 3!).
In Stage 3', whenever the path branches, taken the upper route. Make sure you obtain the "axe" subweapon sometime during the stage. Eventually, you will meet a skeletal snake that is attached to a wall. Nearby is a vine-like cage; use the axe to cut it. It now serves as a platform for Richter to jump to the upper ledges. Continue along the upper ledges until you see a breakable tombstone. Inside is the item that unlocks Symphony of the Night. Return to the main menu to play it.