Gotcha Force

Gotcha Force
Aka: Gacha Fōsu (JP)
Developer: Capcom
Publishers: Capcom
System: GameCube
Release Date
Japan: November 27, 2003
USA: December 3, 2003
Europe: February 20, 2004

Gotcha Force is a fighting / third-person shooter video game developed and published by Capcom for GameCube in 2003.

GCM versions

Name	sha1	Game Code
Gotcha Force (Europe) (En,Fr,De).iso	A94DF10304E6A18827C7325169E9ACE117F17A00	GG4P
Gotcha Force (USA).iso	DFE963E5070B9BEC02BBBEFBA3F038B04DAC953E	GG4E
Gotcha Force (Japan).iso	1B413F219A47E6B3E862A3F7A469A046E88BE893	GG4J
GFRB2.2c.iso	E207F2223ACDE7A7FD287FBAB3C2DE59CF7984E6	GG4P

GFRB2.2c.iso is a rebalanced version of the game made by the team Gotcha Force Rebalanced to play multiplayer battles. The modded iso come from EU iso version.

Game terminology

Word	Meaning
Borg	3D character used in battles.
Stage	3D map used in battles.
Data Crystal	3D items looted at battle's end that can be combined to earn new Borgs.
NPC	Ally or Enemy characters seen during battles.
Gotcha Box	Boxes used to store Borgs.
WareHouse	Game element used to store Borgs when the Gotcha Box is filled up. Borgs can't be selected from WareHouse during battles.

GameCube DVD Architecture

The page GCM (File format) describes in details the GCM file format used by GameCube mini DVD.

GameCube Tooling

The page GameCube Tooling provides softwares and scripts for handling GameCube games ROM / files.

Hardware

GameCube technical specifications

Gekko powerpc CPU user manual: This manual is useful when reverse engineering executables (dol, rel, and so on.). Assembly instructions and Gekko architecture are documented in details.

Another interesting document is the GameCube SDK architecture guide providing technical acronyms definitions and global SDK internal knowledges.

The DSP (Digital Signal Processor allowing to process audio signals - codecs...) has been studied in depth by one of Dolphin Emulator developers team.

Game file formats

Format	Content
ADX	Audio file
AFS	File packing others files (Ongoing researches)
ARC	HSD Files
ARZ	Compressed file
BIN	Unknown
BNR	Banner file format
CHD	DSP part
DOL	SysDolphin executable file (Ongoing researches)
DPK	DSP part
IMG	apploader file
MDT	Uncompressed packed files which contains dialogs
PTL	Particles settings (Ongoing researches)
PZZ	Compressed archive
REF	Unknown (Related to particles?)
SFD	MPEG Sofdec
TPL	Texture Palette Library
TSB	DSP part
TXG	Particles images container (Ongoing researches)

The page file formats reverse engineering is dedicated to methods and researches ongoing on it.

Files and folders tree

USA:

GCM_SYS/
├─ apploader.img
└─ boot.dol
afs_data.afs
├─ *.adx (2113)
├─ *.arc (1369)
├─ *.arz (184)
├─ *.bin (586)
├─ *.chd (4)
├─ *.dpk (4)
├─ *.mdt (6)
├─ ptcl00.ptl
├─ *.pzz (254)
├─ ptcl00.ref
├─ *.sfd (2)
├─ *.tpl (442)
├─ *.tsb (4)
└─ ptcl00.txg
opening.bnr
poq_adx_usa.afs
├─ *.adx (2115)
└─ *.sfd (2)

EU:

 GCM_SYS/
├─ apploader.img
└─ boot.dol
afs_data.afs
├─ *.arc (1334)
├─ *.arz (172)
├─ *.bin (586)
├─ *.chd (4)
├─ *.dpk (4)
├─ *.mdt (1)
├─ *.ptl (1)
├─ *.pzz (253)
├─ *.ref (1)
├─ *.tpl (27)
├─ *.tsb (4)
└─ *.txg (1)
afs_data_a.afs
├─ *.arc (47)
├─ *.arz (12)
├─ *.mdt (5)
├─ *.pzz (2)
└─ *.tpl (415)
afs_data_f.afs
├─ *.arc (47)
├─ *.arz (12)
├─ *.mdt (5)
├─ *.pzz (2)
└─ *.tpl (415)
afs_data_g.afs
├─ *.arc (47)
├─ *.arz (12)
├─ *.mdt (5)
├─ *.pzz (2)
└─ *.tpl (415)
opening.bnr
poq_adx_pal.afs
├─ *.adx (2113)
└─ *.sfd (4) - pal version

JAP:

 GCM_SYS/
├─ apploader.img
└─ boot.dol
afs_data.afs
├─ *.arc (1369)
├─ *.arz (184)
├─ *.bin (586)
├─ *.chd (4)
├─ *.dpk (4)
├─ *.mdt (6)
├─ *.ptl (1)
├─ *.pzz (255)
├─ *.ref (1)
├─ *.tpl (442)
├─ *.tsb (4)
└─ *.txg (1)
opening.bnr
poq_adx.afs
├─ *.adx (2113)
└─ *.sfd (2)

afs_data.afs file naming scheme

You can check full description of all file here: All Assets File Name Index

File naming scheme:

File naming scheme.
Name	Description
pl####*	Borgs files (Player Character)
mn####.tpl	Borgs names in Menus (206)
st##	stage - maps files. We find in position 1,2,3 hitsxx.bin files.
so##	stage object. Building and structures used in battles.
firstld.pzz	Memory card related files (First load - We found the memory card picture in the pzz)
icon.bin	Same than firstld\003C_firstldicon.bin - 3D icon of the memory card
face####	Describe NPCs and properties used when using Special Moves / Abilities
it####_mdl.arz	(90 files) - Item Data Crystal -> #### Match everytime to a Borg requesting multiple Data Crystals
box00_mdl.arc	Gotcha Box
ckpt*	Graphical user interface elements used in battles.
d###_mdl.arc	Menu collection 002: Borgs list, 001: Borg View
deck00_mdl.arc	Edit force menu
entry00_mdl.arc	Interface used to enter player name with characters
optn00_mdl.arc	Option menu
fmg00_mdl.arc	Neo G Red icon used in Story Mode dialogs
rpot##_mdl.arc	Graphical elements used in end of battles
unitall_mdl.arc	Borgs miniatures images used in Edit Force menu, at battle start and so on.
mcmg00_mdl.arc	When loading memory card.
stff*	Main menu
story*	Used in Story Mode progress
trade00_mdl.arc	Used in Trade Menu
set*	Elements to place in the maps (wall, trees and so on.)
tl00_mdl.arc	Used on the corners of the main menu.
gets*	Cinematic used when earning a new Borg. (Blue = Crystal);
gets06_mdl.arc	Cinematic when earning Neo G Red and others colors of Neo G Red.
nwld*	Unimplemented.
staff00_mdl.arc	Credits screen.
vsel00_mdl.arc	Multiplayer screen.
vsel01_mdl.arc	Created forces selection screen before start of battles.
st###_mdl.arz	PNJs images
stm##	Dialogs used in story mode.
sts##	Images used when selecting zones in story mode (face your opponent & defeat the boss)
briff00_mdl.arc	Images used for "VS" page start of fight.
cnd* (3)	Unimplemented files or used for animated titles. The text is inclined and distorted. (defeat enemy gotcha borgs! and so on.)
efct*	Effects - effects used in battles like Shots or Shock.
name00_mdl.arc	Used in "Enter Name" window with grey alphabet.
arrow_mdl.arc	Used probably with a scale for Ally / Enemy health bar.

Game assets implementation

The page implementations group technical details about game assets implementations:

• Borgs
• Data Crystals
• and so on.

You might also want to read:

• Models
• Motions
• Borg - data file

See also our documentation available on github.

Main executable

Depending of which software is used the name of main executable may change since it's not stored in the GCM file: boot.dol / Start.dol and so on.

The page DOL (Gotcha Force) group ongoing researches, technical details and characteristics of the mains Gotcha Force dols.

The main executable embeds MetroTRK, a Target Resident Kernel for embedded systems allowing to remotely debug the game.

We found differents staticly linked libraries in it and in particular HSD engine (HAL Sysdolphin engine). Source files haven't been leaked on the internet but we can find an awesome work realized by "Super Smash Bros. Melee" GameCube community on which we can refer:

-Global description of HSD elements

-Reverse engineering of assemblies rewritten in C

Beta version

The beta version of the game contains differences from the final releases. The 3D map is isometric with 3D elements in it and Borgs descriptions were contained in the screen with two sections: one for characteristics and the other one for the Borg story.

Isometric beta map. Source

Beta Borg description. Source