Thunder Force IV

Thunder Force IV
Also known as: Lightening Force: Quest for the Darkstar (US) Developer: Tecnosoft Publishers: Tecnosoft (JP), Sega (US/EU/AU), Samsung (KR) Platform: Genesis Released in JP: July 24, 1992 Released in US: September 9, 1992 Released in EU: December 1992 Released in AU: 1992 Released in KR: 1992 This game has regional differences. This game has hidden bonus content. This game has a notes page

This article is a work in progress. ...Well, all the articles here are, in a way. But this one moreso, and the article may contain incomplete information and editor's notes.

note: ROM addresses, data, and patch codes apply to the Japanese ROM

To do: Stage 2 theme has a bridge part at the end but the game never gets a chance to play it (main segments are too short, even if you set your speed to the slowest)? You can hear it in the sound test.

Sub-Page

Notes

Hidden, Possibly Dummy, Options

If word $FF8CA4 is nonzero, two new options are shown on the option screen:

STAGE (0:NORMAL GAME)		00
MUTEKIHA NAIYO!

There does not immediately appear to be a cheat to enable this. The first option replaces the play voice sample option.

The first option can be selected normally by scrolling to it; the code for the first option (shared with the play voice sample option) at $10184. The range of values for this option goes from 00 to 10; the code sets the word at $FF8C9E to the BCD value shown.

The second option cannot be selected normally (code at $FB38 skips it and goes to EXIT); you must force it to be selected by setting word $FF8C8E to $0007, then removing the code once it is selected. There is code for this option, at $1021A. Pressing Left/Right will show OFF and ON! options.

The first option does not appear to do anything; the second option's text translates to "there is no invincibility" and thus does nothing.

Unused Strings in Code

Demo Recording?

5B88:4E71 skips over a jump that changes the text PRESS START in the demo gameplay to JOY REC. The jump takes effect if word $FFF2FE <= 0; there is code to clear and a lot of other tests of that value...

Debug Printing?

The code at $3D56 checks word $FFF066; if it's nonzero, it prints some strings TEKI: MAP: SAX: SAY: EASY NORM HARD MANI.

Miscellanea

• On boot, if the word at $420 is nonzero, a different sound driver is loaded; this sound driver starts at $17940. This sound driver does nothing: it sets up the environment as the regular one would but does not make any writes to the sound chips, and then just sits eating up anything fed to it (by overwriting the processing command byte with zero). Its interrupt mode 1 vector (38h) executes di/nop/ei/ret. After that is the three ASCII bytes making up 'Z80', which is immediately followed by (at $17A00) data used by another part of the game.

Bonus Music

Beat the game to add bonus musics to CONFIGURATION MODE's MUSIC menu.

Name	Notes
OMAKE 1
OMAKE 2	Thunder Force AC Stage 4 or Thunder Spirits Stage 4.
OMAKE 3
OMAKE 4
OMAKE 5
OMAKE 6
OMAKE 7
OMAKE 8
OMAKE 9
OMAKE 10

All Weapons Cheat

In the game, pause and press Up, Right, A, Down, Right, A, C, Left, Up, B, Up to equip all weapons. Notice that if you change the controller configuration type, you'll have to alter the inputs for the cheat too.

(Source: Original TCRF research)