Ghosts'n Goblins (Arcade)

So Arthur was chilling with Princess Prin Prin in a graveyard when she suddenly gets nabbed by a giant red demon. Now Arthur has to go through 6 hellish stages -- twice -- and defeat Astaroth to get her back.

MORAL: Do not take your girlfriend to a graveyard for a date.

Debug Switch
The first Japanese revision of the game has a debug mode of sorts. Flip Dip Switch 2A and Arthur will be invincible! This does not work on any other revision of the game.

Unused Music
Track is a short two-second tune that's used in the prototype game after defeating a boss.

Unused Graphics
An alternate design for the Time indicator. This uses a unique font, while the used one just uses the standard font.

It's a cursor. The only place this could be used is the name entry screen.

Unused interrobang and double exclamation point graphics. There's only one point where the latter would be needed, but the game uses two single exclamation points instead.

Programmer Message
A hidden message is on the audio CPU, starting at. Its formatting has been changed for better readability, as the original message has no line breaks.

Cross
The Cross weapon from the Japanese version was changed to a Shield. This is a purely cosmetic change; both weapons have the same properties.

Stage 6
The last section before the two Satan bosses was changed to make the climb up a bit easier. In the Japanese revisions, there are three sitting Red Arremers and one Arremer (in the bottom-right corner) that's invisible until the player gets close enough.

Every other version has one less Red Arremer, their positions have changed, and they all pop out if the player is close. Every cranny with one ogre originally had two in the Japanese game.

Revision Differences
There are seven recognized revisions: three Japanese, three "World", and one U.S. The order appears to be (using the MAME romset names) Japan A, Japan C, World 2, U.S.A., World 1, Japan G, World 3.

Debug Switch
As noted above, the invincibility dip switch only functions in the first Japanese revision.

ROM / RAM Check
In all versions except the first Japanese revision, the integrity of the ROM and RAM are checked before displaying the title screen.

Sound Test
The first Japanese revision has two errors in the Sound Test. First, a track can only be played once per button press (in other revisions, they can be played multiple times without switching). Second, music will never stop playing once it's started, diminishing the usefulness of the Sound Test. In other revisions, the music stops if a sound effect is played.

Boss Scroll Bug
In some versions, scrolling a boss off-screen will destroy the boss object and the game will act as if the boss was killed. This is easiest to do in Stages 4 and 5.

Stage 6 Unicorns
Some revisions add an extra Unicorn at the start of Stage 6, which makes it harder to get past them without taking a hit.

Ladder Skeleton
Present in all international revisions except World B, the last skeleton of Stage 6 is either right next to the ladder or a block away from it. If the skeleton is near the ladder, the player will have to climb up to wake it up, then climb back down to avoid taking a hit.

Stage 6 Boss HP
The two Satan bosses have different HP values between revisions. In the Japanese revisions and World B, they have 4 HP each; in the other revisions, they both have 8 HP.