Under the Microscope: Langrisser IV

My favorite Japanese cheat site has three codes listed for Langrisser IV, the tactical RPG from Career Soft:

• Sound Test: Enter A, Z, Y, X, A, Z, X, Y on the title screen to play music, sound effects, and voices.
• Super Shop: Select “Shop” from the menu, then enter Y, A, Down, X, B to access a shop with almost every item in stock.
• Scenario Selection: On the “Load” screen, enter L, Y, Right, R, R, A to replay scenarios you’ve already completed.

These work, but is the list comprehensive? I checked the game data and found some more codes. Details are below…

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Map selection

Enter this sequence at the title screen:

Up, Left, Right, Down, R, L, Down, Right, X, Z, B

You’ll hear a sound effect if you got it right. Holding down Z on the main menu will now allow you to select your starting map — use the D-pad to navigate. Release Z and choose Start to begin playing.

The first 45 maps are normal locations. The later maps seem to be for testing; some of them just display an image that you can’t interact with.

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Extra MP

Enter this code during gameplay to set your active character’s MP stat to 99:

X, X, B, B, A, A, B, Z

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Extra sounds

After entering the Sound Test code above, enter this button sequence:

A, X, Y, Z, A, X, Z, Y

Now select ADPCM from the Sound Test menu. You’ll be able to select a new directory of sounds, index 042. This plays voice clips from the game’s voice cast.

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Odds and ends

Entering this code during gameplay will display a per-character breakdown of stats on the HUD:

X, C, B, Y, A, Z

Different stats will be displayed if you enter this code and hold down either B or Z.

X, Z, X, Z, Y, Y, R, L

Similarly, entering this code will display DEB or REAL on the HUD:

L, L, R, R, X, Z, Y

You can switch between the two by pressing L+R. The difference between these two modes was presumably meaningful to the game devs, but I couldn’t understand the significance.

The game plays a sound effect if you put in this sequence — it wasn’t clear from the code whether it does something else:

X, Y, B, Y, B, Z, A, Z

If this makes sense to you, leave a comment!

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Technical details

This game uses a fairly typical cheat code detection function (which is loaded at 06011140) to listen for the sequences described above. With variable names added, Ghidra’s decompilation is pretty readable:

int check_cheat_sequence_06011140(const short *cheat_sequence)
{
    int seq_len = 0;
    while (cheat_sequence[seq_len] != 0) {
        seq_len++;
    }

    if (button_history_060c9e6e != p1_pressed_060c0b7a) {
        return 0;
    }

    int history_index = 0x40; 
    while (seq_len > 0) {
        seq_len--;
        history_index--;
        if (button_history_060c9df0[history_index] != cheat_sequence[seq_len]) {
            return 0;
        }
    }

    return 1;
}

In essence, the game keeps track of the buttons you’ve pressed recently in a buffer at 060c9df0. It checks whether the contents of that buffer match a target sequence each time you press a new button.

There’s one exception: the Scenario Selection code (the one from the Japanese cheat site) uses an entirely different mechanism. Its decompilation looks like this:

if (((cheat_buttons_scenarios_060b4b3c)[idx] & p1_pressed_060c0b7a) != 0) {
    if ((idx == 0) || (DAT_060b792e == *(ushort *)(&DAT_060b4b3a + idx * 2))) {
        cheat_counter_scenarios_060b792d++;
        if (cheat_counter_scenarios_060b792d == 6) {
            if ((scenario_flags_060d8f40 == 0) && (scenario_flags_060d8f44 == 0)) {
                cheat_counter_scenarios_060b792d = 6;
                return 0;
            }
            play_sfx_0603a528(1,0);
            /* etc. */
        }
    }
}
else {
    cheat_counter_scenarios_060b792d = 0;
}

Rather than using a buffer, this code uses a counter to track your progress in entering the target sequence. If you get a button right, the counter advances. If you get one wrong, it resets to zero.

Why use different logic for one code? I think this is borrowed from Langrisser III. That game has a very similar Scenario Selection cheat — the button sequence is different, but the decompiled code is identical.

The devs probably just didn’t want to rewrite working code from the last game. Practical!

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Outro

The Map Select cheat above would likely be very useful for somebody attempting to make an English translation patch for Langrisser IV (there’s one in progress for Langrisser III). If that’s you, get in touch — I’ll share my Ghidra file.

For previous explorations in hacking Saturn RPGs, see my articles on:

• Riglordsaga 2, Shiroki Majo, & Magic Knight Rayearth
• Grandia Digital Museum, Samurai Spirits Bushido Retsuden, & Marica: The Real World