Castlevania II: Simon's Quest

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How it plays
Across the series
Related
Mechanics
References
Sources

Castlevania II: Simon’s Quest is Konami’s sequel to Castlevania. Konami dates it to 28 August 1987 in Japan, where it came out for the Famicom Disk System as Dracula II: Noroi no Fūin, and to 24 November 1988 in North America, on the NES¹. The player is Simon Belmont, who searches for the five missing parts of Count Dracula’s body and then goes to Dracula’s castle to fight him again².

Konami describes the game as a break from the stage-by-stage format of 2D action games. Simon travels from town to town after items scattered across the land, clears dungeons, and beats bosses, a progression Konami likens to a role-playing game³. Townspeople give clues, though some of them lie, and merchants sell weapons and items for hearts⁴. Simon’s experience rating grows as he survives⁵. Day turns to night: the towns empty and the shops close, and enemies grow stronger but give more experience and hearts⁶.

Hitoshi Akamatsu, the creator of Castlevania, gave the game its American title, by the account of a developer he mentored⁷. Asked by the same developer about Metroid, Akamatsu said he had been thinking more of Konami’s own Maze of Galious⁸. By the account of Kinuyo Yamashita, who scored Castlevania, Kenichi Matsubara composed the music⁹.

Computer Entertainer recommended the game in January 1989, saying it “outdoes its predecessor in every way” and leans much more on adventure¹⁰. In a 2005 retrospective for RPGamer, Jordan Jackson praised the music but found its areas and enemies repetitive and much of the townsfolk’s talk strange¹¹. He called it a template for later games, Castlevania: Symphony of the Night among them¹². The developer Akamatsu mentored recalled that Akamatsu’s sequels to Castlevania sold poorly¹³.

#How it plays

Every jump from the ground leaves at the same speed and slows under gravity, so a tap and a hold of the button rise the same height¹⁴. Once Simon leaves the ground he can’t steer. The jump carries him the way he held at take-off, or straight up¹⁵.

A hit turns Simon toward the enemy and throws him up and away from it, and the jump’s gravity brings him down¹⁶.

#Day and night

A clock of days, hours, and minutes runs as Simon plays, and at fixed hours it turns day to night and night to day¹⁷. At night most enemies outside the mansions start with double their hit points¹⁸. The zombies that walk the towns at night first hopped, like jiangshi, by the same developer’s account, until people said they were too strong and Akamatsu made them walk¹⁹.

#Hearts and whips

Hearts are both ammunition and money. Throwing a knife and buying from a merchant spend the same count, and a merchant won’t sell what Simon can’t afford²⁰. Merchants also sell whips, and a bought whip replaces the one Simon holds outright²¹.

#Passwords

A password saves progress. It keeps Simon’s level, items, whip, and the day, but not his hearts or experience²². Part of each password comes from the frame it was made on, so the same progress can be written more than one way²³. A password that fails its check is refused²⁴.

#Across the series

Against Castlevania, Simon’s Quest changes:

the jump, from a fixed table of steps to a speed under gravity¹⁴;
the hit, from a short hop to a launch¹⁶;
the whip’s upgrades, from drops to purchases²¹.

It keeps the jump’s fixed direction¹⁵. Konami counts it the series’ second game³, and a couple of its tunes recur in later ones¹².

Mechanics

Mechanic	Kind	How
Jump	One speed	every jump leaves the ground at the same speed and slows under gravity
Gravity	One gravity	one gravity on every jump, with a capped fall
Air control	Fixed	the jump keeps the direction held at take-off, as in Castlevania
Knockback	Launch	a hit throws Simon up and back, falling like a jump
Time of day	Game clock	a running clock turns day to night and back, and at night most enemies have double hit points
Weapon energy	Shared pool	hearts pay for the subweapons and for the merchants' wares
Whip upgrade	Bought	merchants sell whips, and a bought whip replaces the old one outright
Password and battery save	Password with a check value	a password keeps Simon's items, whip, and day, but not his hearts
Variable jump height	None	a tap and a hold rise the same height

Every claim about this game, by concept (25)

general	Konami dates Simon's Quest's release in Japan to 28 August 1987, on the Famicom Disk System as Dracula II: Noroi no Fūin; in North America to 24 November 1988, on the NES; and in Europe to February 1990, on the NES.	Publisher
	Konami calls Simon's Quest the second game in the series and describes it as a break from the stage-clear format common to 2D action games: the player travels from town to town after items scattered across the land, clears dungeons, and beats bosses, a progression it likens to a role-playing game. It also names day and night that change with time among the game's ambitious systems.	Publisher
	The player is Simon Belmont, who searches for Count Dracula's five missing body parts and, once he has them, goes to Dracula's castle to fight the count again.	Manual
	The manual says Simon's experience rating grows the longer he survives, and his soul grows stronger with it.	Manual
	In the towns Simon talks to townspeople for clues, though some of them are pranksters who give false information, and merchants sell weapons and other items for hearts.	Manual
	At night the townspeople are gone and the stores and churches are closed, and enemies are more powerful but give more experience points and hearts.	Manual
	A former Konami developer whom Hitoshi Akamatsu, the creator of Castlevania, mentored recalls that Akamatsu came up with the American title, Simon's Quest, himself.	Web
	Asked whether Metroid influenced Simon's Quest, Akamatsu answered, by the same developer's account, that he was thinking more of Konami's own Maze of Galious.	Web
	By the same developer's account, the zombies in the towns at night first hopped, like jiangshi, and Akamatsu reluctantly made them walk after people said they were too strong.	Web
	The same developer recalls that Akamatsu's sequels to Castlevania sold poorly, so that he was demoted to working in one of Konami's game centers, and that he then quit.	Web
	By the account of Kinuyo Yamashita, who scored Castlevania, Kenichi Matsubara composed the music. She says she was working on other games at the time and that her superior removed her from Castlevania II.	Interview
	Computer Entertainer's January 1989 review recommended Simon's Quest, saying it outdoes its predecessor in every way and leans much more on adventure, with clues from villagers and weapons to buy; it counted the change from day to night, when creatures appear in great numbers, among its touches.	Magazine
	Jordan Jackson's 2005 retrospective review for RPGamer praised the music but found most areas palette swaps of others, with the same enemies repeated, and much of what the townsfolk say strange.	Web
	The same review calls Simon's Quest a template for later games such as Castlevania: Symphony of the Night, and says a couple of its tunes recur in later games of the series.	Web
Air control	In Simon's Quest the take-off sets Simon's horizontal speed to 1 px/frame toward a held Left or Right, or 0, and the jumping state reads only B, for the whip, so the jump keeps its direction as in Castlevania.	Code
Jump	Simon's Quest replaces Castlevania's step table with a speed and gravity; a jump from the ground takes off at 4 px/frame up, every airborne frame adds 0.21875 px/frame² of gravity, and a fall is capped at 3 px/frame, where Castlevania steps a fixed 20-entry table and falls past its end at 8 px/frame.	Code
Knockback	Simon's Quest turns an enemy's touch into a launch, not Castlevania's table arc; as in Castlevania, Simon is turned to face the enemy and moved away from it, here at 2.5 px/frame up and 1 px/frame back, held in a hurt state for 32 frames that runs the jump's speed and gravity code before he falls normally.	Code
Password and battery save	Simon's Quest's password packs 10 bytes: 7 of state, the byte FoxCunning labels Simon's level, the day count in BCD, the laurel and garlic counts in 4 bits each (the encoder writes a count above 8 as 8), the bytes labeled body parts, misc items 1, and misc items 2, and the whip level; then the 16-bit sum of those 7 as a check value; then a scramble byte. Hearts are not kept: accepting a password zeroes the bytes FoxCunning labels hearts and experience, sets HP to 48 and lives to 3, and zeroes $30 and $50-$57 (labeled the map type, scene, sub-room, and scroll position), $82 (night), $84, and $85 (the time wait counter and the minute).	Code
	Simon's Quest writes the 10 bytes, 80 bits, as 16 characters of 5 bits each, high bit first, so the scramble byte fills the last 8 bits; the screen draws a value n as tile n + 1 of CHR bank 16, where by the atlas's reading of the tiles 1-36 are A-Z and 0-9. Since the scramble adds up to 4 to characters 1-14, they can show all 36 (computed), and characters 15 and 16 only A-Z and 0-5. On the entry grid, pressing A on cells 0-35 enters that symbol, cells 36 and 37 step the cursor back and forward, and a later cell submits.	Code
	To make a password, Simon's Quest sums the 7 state bytes into a 16-bit check value and takes a scramble from the frame counter: its low 4 bits number one of 16 tables of 14 XOR values, and its low 3 bits pick an add from 0, 1, 2, 3, 4, 1, 2, 3. After packing, characters 1-14 are XORed with the table and then have the add added; characters 15 and 16 carry the add and the table number unscrambled. Since the add follows from the table number, one state has at most 16 passwords (computed).	Code
	On entry Simon's Quest rejects a password with any of its 16 characters blank. Otherwise it subtracts the add from characters 1-14, XORs them, unpacks the 10 bytes, and accepts only when both bytes of the sum match the 7 state bytes again, the level is below 7, the body-parts and misc-items-2 bytes are below $80, misc items 1 is below $10, the whip level is below 5, both of the day's digits are 0-9, and laurels and garlics are each at most 8. A rejection writes MISS and ENTRY to the screen, plays sound $24, and after 128 frames brings back the ENTER YOUR PASSWORD prompt and returns to input, writing nothing to the entered characters on the way; an acceptance writes ENTRY COMPLETED.	Code
Time of day	Simon's Quest keeps a clock of days, hours, and minutes in BCD that advances one minute every 15 frames outside the stopped cases, and when the hour reaches 6 or 18 it starts the day-night transition; a day is 24 hours.	Code
Time of day	In Simon's Quest an enemy placed while it's night starts with double the hit points its level data gives, except a few object types and in the mansions.	Code
Weapon energy	In Simon's Quest hearts are both subweapon ammunition and money; the knives' routine and a merchant's deal both call one routine that subtracts a BCD price from the heart count and refuses when there aren't enough, and the knives' routine passes it 1 heart, or 2 for one of them.	Code
Whip upgrade	Simon's Quest sells whips; a paid merchant deal whose index is $18 or above sets the whip level outright from the item, where Castlevania raises it one level per whip that a bonus drops.	Code

References

^Konami dates Simon's Quest's release in Japan to 28 August 1987, on the Famicom Disk System as Dracula II: Noroi no Fūin; in North America to 24 November 1988, on the NES; and in Europe to February 1990, on the NES.PublisherKonami, Dracula II history · Konami, Simon's Quest US history · Konami, Simon's Quest EU history
How we know
発売日：1987年8月28日
game entry, release and platform lines · archived copy ↗
ファミリーコンピュータディスクシステム
game entry, platform line · archived copy ↗
Nov 24, 1988
title header, release line · archived copy ↗
Feb. 1990
title header, release line · archived copy ↗
The quote matches our archived copy.
Checked by a second AI model, 2026-10-27.
In the claim ledger
^The player is Simon Belmont, who searches for Count Dracula's five missing body parts and, once he has them, goes to Dracula's castle to fight the count again.ManualSimon's Quest NES manual
How we know
take on the role of Simon Belmont on his quest to uncover Count Dracula's five missing body parts … proceed to Dracula's castle, where you'll again duel to the death with the count
3, Basic Play · archived copy ↗
The quote matches our archived copy.
Checked by a second AI model, 2026-10-27.
In the claim ledger
^ a bKonami calls Simon's Quest the second game in the series and describes it as a break from the stage-clear format common to 2D action games: the player travels from town to town after items scattered across the land, clears dungeons, and beats bosses, a progression it likens to a role-playing game. It also names day and night that change with time among the game's ambitious systems.PublisherKonami, Dracula II history
How we know
シリーズ2作目 … 2Dアクションによくあるステージクリア型ではなく … 街から街へと移動し、ダンジョンを攻略し、ボスを倒す … さながらRPGのような進行になっている … 時間によって昼夜が入れ替わるなど、野心的なシステムを数多く採用した
Game section · archived copy ↗
The quote matches our archived copy.
Checked by a second AI model, 2026-10-27.
In the claim ledger
^In the towns Simon talks to townspeople for clues, though some of them are pranksters who give false information, and merchants sell weapons and other items for hearts.ManualSimon's Quest NES manual
How we know
Stop and talk to the townspeople for helpful clues … some of the townspeople are pranksters, and will give Simon falsified information … merchants who'll sell you weapons and other mystical items. Your purchasing power depends on how many hearts you've collected
3, Basic Play · archived copy ↗
The quote matches our archived copy.
Checked by a second AI model, 2026-10-27.
In the claim ledger
^The manual says Simon's experience rating grows the longer he survives, and his soul grows stronger with it.ManualSimon's Quest NES manual
How we know
the longer you survive, the greater your experience rating, and the stronger your vulnerable soul will become
3, Basic Play · archived copy ↗
The quote matches our archived copy.
Checked by a second AI model, 2026-10-27.
In the claim ledger
^At night the townspeople are gone and the stores and churches are closed, and enemies are more powerful but give more experience points and hearts.ManualSimon's Quest NES manual
How we know
Townspeople are conspicuously absent during the night, and stores and churches are closed. … Enemies are also more powerful at night, and as a result you gain more experience points and hearts when you defeat them.
3, Basic Play, Night-Time · archived copy ↗
The quote matches our archived copy.
Checked by a second AI model, 2026-10-27.
In the claim ledger
^A former Konami developer whom Hitoshi Akamatsu, the creator of Castlevania, mentored recalls that Akamatsu came up with the American title, Simon's Quest, himself.Webshmuplations, Castlevania developer commentary
How we know
Hitoshi Akamatsu, the creator of the legendary Castlevania, was my boss
introduction · archived copy ↗
in America it’s called Simon’s Quest, which Akamatsu came up with himself.
Castlevania II – Simon's Quest · archived copy ↗
The quote matches our archived copy.
In the claim ledger
^Asked whether Metroid influenced Simon's Quest, Akamatsu answered, by the same developer's account, that he was thinking more of Konami's own Maze of Galious.Webshmuplations, Castlevania developer commentary
How we know
I asked Akamatsu whether Metroid was an influence on the development … I was thinking more of Konami’s own
Castlevania II – Simon's Quest · archived copy ↗
The quote matches our archived copy.
In the claim ledger
^By the account of Kinuyo Yamashita, who scored Castlevania, Kenichi Matsubara composed the music. She says she was working on other games at the time and that her superior removed her from Castlevania II.InterviewGreening, Yamashita interview
How we know
Kenichi Matsubara, a person who exclusively composed music, took charge of the score for the sequel. … regrettably my superior removed me from the role of … I was taking charge of other games at the time
answer on the series' later music · archived copy ↗
The quote matches our archived copy.
Checked by a second AI model, 2026-10-27.
In the claim ledger
^Computer Entertainer's January 1989 review recommended Simon's Quest, saying it outdoes its predecessor in every way and leans much more on adventure, with clues from villagers and weapons to buy; it counted the change from day to night, when creatures appear in great numbers, among its touches.MagazineComputer Entertainer 7-10
How we know
outdoes its predecessor in every way … much more reliance on adventure gaming elements … changes from day to night when the evil creatures appear in great numbers … Recommended.
PDF p. 11, NINTENDO Software · archived copy ↗
The quote matches our archived copy.
In the claim ledger
^Jordan Jackson's 2005 retrospective review for RPGamer praised the music but found most areas palette swaps of others, with the same enemies repeated, and much of what the townsfolk say strange.WebRPGamer, Simon's Quest Retroview
How we know
The music is one of the places where the game excels.
music paragraph · archived copy ↗
most of the game’s areas are merely pallete swaps of other locations … this repetition also applies to the enemies
visuals paragraph · archived copy ↗
a lot of what the townsfolk say seems rather strange
menus and localization paragraph · archived copy ↗
The quote matches our archived copy.
In the claim ledger
^ a bThe same review calls Simon's Quest a template for later games such as Castlevania: Symphony of the Night, and says a couple of its tunes recur in later games of the series.WebRPGamer, Simon's Quest Retroview
How we know
it served as a template for great games like
closing paragraph · archived copy ↗
became a very rough blueprint for some amazing games to come
opening paragraph · archived copy ↗
a couple of the tunes became recurring songs in future games
music paragraph · archived copy ↗
The quote matches our archived copy.
In the claim ledger
^The same developer recalls that Akamatsu's sequels to Castlevania sold poorly, so that he was demoted to working in one of Konami's game centers, and that he then quit.Webshmuplations, Castlevania developer commentary
How we know
Akamatsu’s sequels to Castlevania sold poorly, so he was demoted to working in one of Konami’s game centers, and then he quit.
On Director Hitoshi Akamatsu · archived copy ↗
The quote matches our archived copy.
In the claim ledger
^ a bSimon's Quest replaces Castlevania's step table with a speed and gravity; a jump from the ground takes off at 4 px/frame up, every airborne frame adds 0.21875 px/frame² of gravity, and a fall is capped at 3 px/frame, where Castlevania steps a fixed 20-entry table and falls past its end at 8 px/frame.Code“Castlevania II - Simon's Quest (USA)” · “Castlevania (USA) (Rev 1)”
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 3 $88D9-$892A, the take-off: Y speed $036C.$037E = −4.0 ($FC.$00), the action set to jumping, and the held d-pad read into the X speed and facing; bank 3 $89D6-$8A0D, each jumping frame: zero the speed on a ceiling, add $38 to the speed's fraction ($DFE4), and cap a fall at 3.0; bank 7 $DFE4-$DFF9, a 16-bit add of $0008 to object X's Y speed. We don't reproduce the bytes.
In the cartridge (“Castlevania (USA) (Rev 1)”): Castlevania's jump table, 20 signed steps between a $80 and a $81 marker (castlevania/jump-table); Castlevania's fall past the table's end, 8 px per frame (castlevania/table-end-fall). We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^ a bIn Simon's Quest the take-off sets Simon's horizontal speed to 1 px/frame toward a held Left or Right, or 0, and the jumping state reads only B, for the whip, so the jump keeps its direction as in Castlevania.Code“Castlevania II - Simon's Quest (USA)” · “Castlevania (USA) (Rev 1)”
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 3 $8905-$8928: held Right ($F7 bit 0) sets X speed $6D.$6C = 1.0, Left −1.0 and facing left, neither 0; bank 3 $89CD-$8A0D, the jumping state: a new B press ($F5 AND $40) goes to the whip; the rest is the vertical speed. We don't reproduce the bytes.
In the cartridge (“Castlevania (USA) (Rev 1)”): Castlevania's take-off copying the held Left and Right into Simon's direction (castlevania/jump-start). We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^ a bSimon's Quest turns an enemy's touch into a launch, not Castlevania's table arc; as in Castlevania, Simon is turned to face the enemy and moved away from it, here at 2.5 px/frame up and 1 px/frame back, held in a hurt state for 32 frames that runs the jump's speed and gravity code before he falls normally.Code“Castlevania II - Simon's Quest (USA)” · “Castlevania (USA) (Rev 1)”revised
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 1 $8844-$8854, after the hit's damage: facing $0420 = 1 if the enemy's X is at or right of Simon's, else 0; then jump to $D36F; bank 7 $D36F-$D3A7: X speed −1.0 if $0420 is nonzero, else +1.0; Y speed −2.5 ($FD.$80); action 6; a 32-frame counter $04B0 = $20; bank 3 $8A0E-$8A21, action 6: count down $04B0, running the jumping physics at $89D6, then action 2. We don't reproduce the bytes.
In the cartridge (“Castlevania (USA) (Rev 1)”): Castlevania's hit, which points Simon's arc at a second table (castlevania-line/knockback). We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-21.
Revised after a check by a second AI model, 2026-10-21.
In the claim ledger
^Simon's Quest keeps a clock of days, hours, and minutes in BCD that advances one minute every 15 frames outside the stopped cases, and when the hour reaches 6 or 18 it starts the day-night transition; a day is 24 hours.Code“Castlevania II - Simon's Quest (USA)”
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 7 $D767-$D7C9: no tick in map type 5, in Simon's action $0B, while $34 is set, or while $8F stops time; else a counter $84 to 15, then minute $85 + 1 to 60, hour $86 + 1 to 24 (then day $83 + 1, up to 99); hour 6 or 18 jumps to the transition; bank 7 $CED8-$CEDD, in the transition, IsNightTime $82 flipped with XOR 1. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^In Simon's Quest an enemy placed while it's night starts with double the hit points its level data gives, except a few object types and in the mansions.Code“Castlevania II - Simon's Quest (USA)” · FoxCunning/Castlevania2
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 1 $810D-$814C: if IsNightTime ($82), and the type isn't $21, $22, $25-$27, $2D-$2F, or $34, and map type ($30) isn't 1, the HP byte is shifted left once before it's stored in $04C2. We don't reproduce the bytes.
```
531LevelData_Stairs_1_Mansions_2_3_11_12:
```
bank_2.asm line 531 at 2abe12c · upstream ↗
Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^By the same developer's account, the zombies in the towns at night first hopped, like jiangshi, and Akamatsu reluctantly made them walk after people said they were too strong.Webshmuplations, Castlevania developer commentary
How we know
The zombies that appear in the towns at night in Simon’s Quest originally hopped around … People said they were too strong though, so Akamatsu reluctantly toned them down to just walking zombies.
Castlevania II – Simon's Quest · archived copy ↗
The quote matches our archived copy.
In the claim ledger
^In Simon's Quest hearts are both subweapon ammunition and money; the knives' routine and a merchant's deal both call one routine that subtracts a BCD price from the heart count and refuses when there aren't enough, and the knives' routine passes it 1 heart, or 2 for one of them.Code“Castlevania II - Simon's Quest (USA)”revised
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 7 $D856-$D891: the subweapon wrapper ($D856) and the check ($D867), a BCD subtraction from hearts $48/$49 that stores the result only if it doesn't go below 0; bank 7 $D8D6-$D8E4, the knives: cost 2 for subweapon 3, else 1, through $D856; bank 7 $ED90-$ED99, a merchant deal calling the same $D867 with its price. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-21.
Revised after a check by a second AI model, 2026-10-21.
In the claim ledger
^ a bSimon's Quest sells whips; a paid merchant deal whose index is $18 or above sets the whip level outright from the item, where Castlevania raises it one level per whip that a bonus drops.Code“Castlevania II - Simon's Quest (USA)” · “Castlevania (USA) (Rev 1)”
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 7 $ED9E-$EDA3, after the hearts are paid, item $18 and up branch to $EDED; bank 7 $EDED-$EDFD: whip level $0434 = (item AND $1F) − 7. We don't reproduce the bytes.
In the cartridge (“Castlevania (USA) (Rev 1)”): Castlevania's drop rule (castlevania-line/whip-drop). We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^Simon's Quest's password packs 10 bytes: 7 of state, the byte FoxCunning labels Simon's level, the day count in BCD, the laurel and garlic counts in 4 bits each (the encoder writes a count above 8 as 8), the bytes labeled body parts, misc items 1, and misc items 2, and the whip level; then the 16-bit sum of those 7 as a check value; then a scramble byte. Hearts are not kept: accepting a password zeroes the bytes FoxCunning labels hearts and experience, sets HP to 48 and lives to 3, and zeroes $30 and $50-$57 (labeled the map type, scene, sub-room, and scroll position), $82 (night), $84, and $85 (the time wait counter and the minute).Code“Castlevania II - Simon's Quest (USA)” · FoxCunning/Castlevania2revised
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 4 $AF21-$AF61, EncodePassword_Compress: $8B, $83, $4C and $4D (each ANDed with $0F, then 8 if 8 or more, garlics shifted into the high nibble), $91, $92, $4A, and $0434 copied to $0520-$0526; bank 4 $AE3E-$AE5D, EncodePassword_CreateChecksum: $0520-$0526 summed with carry into $0527 (high) and $0528 (low); bank 4 $AEFB-$AF20, EncodePassword_CreateAddSub and its table: the add shifted into the high nibble of $0529, the XOR number in the low; bank 4 $AD47-$ADB5, the accepted path: $0434 kept on the stack across a JSR to $C5A1, then a JSR to $C419, $90, $4F, $33, $1E, $82, $30, $50-$57, $84, and $85 zeroed, $80 = $30, $31 = 3; bank 7 $C419-$C423, ResetHeartsAndExp: zero to $48, $49, $46, $47. We don't reproduce the bytes.
```
48	Edigits0011 = $46						; $46
⋮
51	HeartsDigits1100 = $49					; $49
```
globals.inc lines 48–51 at 2abe12c · upstream ↗
```
33	CurrentLevelMapType = $30							; $30
34	RemainingLives = $31								; $31
```
globals.inc lines 33–34 at 2abe12c · upstream ↗
```
52	InventoryMiscItems2 = $4A				; $4A
⋮
54	InventoryNumLaurels = $4C				; $4C
55	InventoryNumGarlics = $4D				; $4D
⋮
58	CurrentLevelSceneNumber = $50					; $50
59	CurrentLevelSubRoomNumber = $51					; $51
60	CurrentXScrollingPositionPixels = $53			; $53
61	CurrentXScrollingPositionScreens = $54			; $54
62	CurrentYScrollingPositionPixels_Mod240 = $56	; $56
63	Current_WhatUnknown57 = $57						; $57
```
globals.inc lines 52–63 at 2abe12c · upstream ↗
```
88	CurrentHP = $80					; $80
⋮
90	IsNightTime = $82				; $82
91	CurrentDayBCD = $83				; $83
92	CurrentTimeWaitCounter = $84	; $84
93	CurrentMinuteBCD = $85			; $85
```
globals.inc lines 88–93 at 2abe12c · upstream ↗
```
102	InventoryBodyParts1 = $91						; $91
103	InventoryMiscItems1 = $92						; $92
```
globals.inc lines 102–103 at 2abe12c · upstream ↗
```
258	CurrentWhipLevel = $0434				; $0434
```
globals.inc line 258 at 2abe12c · upstream ↗
```
97	CurrentLevel = $8B								; $8B
```
globals.inc line 97 at 2abe12c · upstream ↗
```
301	PasswordLevel = $0520				; $0520
302	PasswordCurrentDayBCD = $0521		; $0521
303	PasswordLaurelsGarlics = $0522		; $0522
304	PasswordBodyparts = $0523			; $0523
305	PasswordMiscItems1 = $0524			; $0524
306	PasswordMiscItems2 = $0525			; $0525
307	PasswordWhipLevel = $0526			; $0526
308	PasswordChecksumHi = $0527			; $0527
309	PasswordChecksumLo = $0528			; $0528
310	PasswordXorAdd = $0529				; $0529
```
globals.inc lines 301–310 at 2abe12c · upstream ↗
Checked against the evidence by its author, an AI model, 2026-10-22.
Revised after a check by a second AI model, 2026-10-22.
In the claim ledger
^To make a password, Simon's Quest sums the 7 state bytes into a 16-bit check value and takes a scramble from the frame counter: its low 4 bits number one of 16 tables of 14 XOR values, and its low 3 bits pick an add from 0, 1, 2, 3, 4, 1, 2, 3. After packing, characters 1-14 are XORed with the table and then have the add added; characters 15 and 16 carry the add and the table number unscrambled. Since the add follows from the table number, one state has at most 16 passwords (computed).Code“Castlevania II - Simon's Quest (USA)”
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 4 $AE24-$AE3D, EncodePassword: compress, checksum, choose the scramble, pack, XOR, add; bank 4 $AE3E-$AE5D: 16-bit sum of $0520-$0526; bank 4 $AEFB-$AF20: FrameCounter ($1D) AND 7 indexes the 8-entry add table, AND $0F gives the XOR number; bank 4 $B205-$B327, Password_DoXorring: 16 pointers to 14-byte tables, each value below $20, XORed into $0530-$053D; bank 4 $AEE9-$AEFA, EncodePassword_DoAdding: the add added to $0530-$053D. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-22.
Checked by a second AI model, 2026-10-22.
In the claim ledger
^On entry Simon's Quest rejects a password with any of its 16 characters blank. Otherwise it subtracts the add from characters 1-14, XORs them, unpacks the 10 bytes, and accepts only when both bytes of the sum match the 7 state bytes again, the level is below 7, the body-parts and misc-items-2 bytes are below $80, misc items 1 is below $10, the whip level is below 5, both of the day's digits are 0-9, and laurels and garlics are each at most 8. A rejection writes MISS and ENTRY to the screen, plays sound $24, and after 128 frames brings back the ENTER YOUR PASSWORD prompt and returns to input, writing nothing to the entered characters on the way; an acceptance writes ENTRY COMPLETED.Code“Castlevania II - Simon's Quest (USA)” · FoxCunning/Castlevania2revised
How we know
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 4 $AD16-$AD46, DecodePassword_VerifyIt: any 0 at $0540-$054F goes to the error; each value less 1 into $0530-$053F; the error sends string $59, sets the delay to $80, plays $24; bank 4 $AE15-$AE23, DecodePassword: read the scramble, subtract, XOR, unpack, check; bank 4 $AFA6-$AFC6, DecodePassword_LastByte: XOR number from $053F's low 4 bits, add from $053F bit 4 and $053E bits 0-2; bank 4 $AF94-$AFA5, DecodePassword_DoSubbing: the add subtracted from $0530-$053D; bank 4 $B0DA-$B204, DecodePassword_Convert6_to_8: the 5-bit values back into $0520-$0528; bank 4 $AE5E-$AEE0, DecodePassword_VerifyChecksum and its maxima $07, $FF, $FF, $80, $10, $80, $05: the sum recomputed and both bytes compared, level below 7, bytes 3-6 below their maxima, each day nibble below $0A, each laurel and garlic nibble below 9; on a pass, string $5A and sound $25; bank 4 $ADB6-$ADC5: count the delay down, send string $5B, set state 2; bank 4 $ADFE-$AE01, where the error jumps: increment the state ($04EF), 3 to 4; bank 4 $AAA2-$AABD, the screen's dispatch on $04EF: state 2 is $AB0C, the input handler, 3 is $AD16, the check, 4 is $ADB6, the wait. We don't reproduce the bytes.
```
327	PasswordInputtedCode0 = $0540		; $0540
```
globals.inc line 327 at 2abe12c · upstream ↗
In the cartridge (“Castlevania II - Simon's Quest (USA)”): bank 7 $C9EA-$CA03, string $59: tiles spelling MISS, then ENTRY and two punctuation tiles; bank 7 $CA04-$CA1D, string $5A: ENTRY, then COMPLETED. We don't reproduce the bytes.
```
1434	.word (PPU_Text_StringsList_59_bank7_PasswordError) ;C9EA (1C9EA) ([8:8][A:9])
1435	.word (PPU_Text_StringsList_5A_bank7_EntryCompleted) ;CA04 (1CA04) ([8:8][A:9])
1436	.word (PPU_Text_StringsList_5B_bank7_EnterYourPassword) ;CA1E (1CA1E) ([8:8][A:9])
```
bank_7.asm lines 1434–1436 at 2abe12c · upstream ↗
Checked against the evidence by its author, an AI model, 2026-10-22.
Revised after a check by a second AI model, 2026-10-22.
In the claim ledger

Sources

Code

1988. “Castlevania II - Simon's Quest (USA).” · licence, all uses
1987. “Castlevania (USA) (Rev 1).” · licence, all uses
FoxCunning. 2022. “Castlevania 2 - Bloodlust: a full disassembly and hack of Castlevania II: Simon's Quest.” Commit 2abe12c. FoxCunning/Castlevania2 @ 2abe12c · licence, all uses

Primary

Entertainment, Konami Digital. 2026. “Castlevania Portal: Dracula II: Noroi no Fūin (1987 Famicom Disk System).” original · archived · licence, all uses
Entertainment, Konami Digital. 2026. “Castlevania Portal: Castlevania II Simon's Quest (United States).” original · archived · licence, all uses
Entertainment, Konami Digital. 2026. “Castlevania Portal: Castlevania II Simon's Quest (Europe).” original · archived · licence, all uses
Konami. 1988. “Castlevania II: Simon's Quest instruction booklet (NES, North America).” original · archived · licence, all uses
Greening, Chris. 2009. “Kinuyo Yamashita Interview: Castlevania Composer.” original · archived · licence, all uses

Secondary

shmuplations. 2018. “Castlevania – Developer Commentary.” original · archived · licence, all uses
Computer Entertainer editors. 1989. “Computer Entertainer, vol. 7, no. 10 (January 1989).” Computer Entertainer, vol. 7, no. 10, p. 11. The Video Game Update / Computer Entertainer. original · archived · licence, all uses
Jackson, Jordan. 2005. “Castlevania II: Simon's Quest Retroview.” original · archived · licence, all uses