Overview

Game Overview

MegaMan Legends is a unique 3D action-adventure game, released across multiple platforms: PSX, PSP (Japan-only), and PC (Japan-only). This documentation focuses primarily on the PSX version, as it is the most widely available version.

The PSX version is organized into two main folders: DAT and COMMON, where most of the game’s assets are stored.

While the PC version uses a different archive format, the actual game data in the PC version shares similarities with the PSX version, especially the internal assets (such as meshes, textures, etc.).

The PSP version contains mostly the same assets as the PSX version, with some Japan-exclusive side content.

PSX Version: File Structure

On the PSX game disc, the game files are organized as follows:

• ROCK_NEO.EXE: The main game executable.
• COMMON Folder: Contains the player character mesh, the title screen assets, and UI sprites such as the pause menu.
• DAT Folder: Contains assets broken down by scenes, such as stage models, enemy meshes, NPC data, and textures.

COMMON Folder

The COMMON folder holds data that is reused across multiple scenes. Some of the notable assets include:

• Player Character Mesh (MegaMan): This is where the player character’s 3D model is stored.
• Title Screen: Assets for the game’s title screen are contained here.
• Sprites and UI Elements: Common sprites, such as those used in the pause menu, are also found here.

DAT Folder

The DAT folder is structured around scenes in the game. Each scene is broken into multiple acts. For example:

• Scene 3: Contains Act 0, Act 1, Act 2, Act 3, Act 4, and Act 5.
  • Each act contains specific models and textures for that scene.
  • Duplicated Assets: Meshes and textures are often duplicated between acts to allow the game to load data sequentially into memory, avoiding issues with limited RAM on the PSX.

File Format Documentation

Mesh Formats

The mesh format used for 3D models in MegaMan Legends typically follows this structure:

• PBD Mesh Data for the player character
• EBD Mesh Data for the scene entities

Texture Formats

Textures are stored as compressed images. The compression algorithm used on the PSX version is unique to the hardware, requiring custom decompression scripts.

• TIM Texture format for the PlayStation, uses the same elements packed differently
  • Image + Palette compressed
  • Image + Palette uncompressed
  • Image Compressed
  • Palette Only Uncompressed

Compression Formats

The game uses a variety of compression techniques to store data efficiently on the disc. Some of these include:

• LZ77r Compression: Modified version of an LZ77 with a fixed 0x2000 byte window size