Taking apart Tekken 4
Tekken 4 (PS2) from the disc up: the archive, movesets, stages, models and sound, in the order a reader needs them.
9 parts, in reading order
- QL-0013
Part 1: Tekken 4 (PS2): a map of what’s known
A status map of the Tekken 4 (PS2) teardown as of 2026-10-22: what is decoded and proven in game, what is decoded but unproven, what is partly understood and what is still unknown, across the archive, movesets, characters, stages and sound. Also the claims that turned out wrong, and the open problems in order of how much they block.
Rev. A - QL-0014
Part 2: Tekken 4’s 2.57 GB archive keeps its index in the executable
Tekken 4 (PS2) stores almost everything in one 2.57 GB file, DATA.BIN, with no index inside it. The index is a 1,121-entry table in the game’s executable, and the archive’s only protection is a reversible flip of each file’s first 4 KB. Both are decoded, every checksum passes, and a modified disc that appends new files to the archive boots and plays.
Rev. B - QL-0015
Part 3: Tekken 4’s moveset files, decoded and edited in game
How Tekken 4 (PS2) stores each fighter’s moves: an LZSS-compressed “Character Data” file of twenty tables. The format is decoded well enough to rebuild all 22 stock movesets byte for byte, and edits made with it work in game: a move’s damage changed, a button rerouted, a brand-new move added, and one fighter’s whole moveset run on another’s body.
Rev. B - QL-0016
Part 4: Tekken 4’s stage format, and building a new stage from scratch
Each Tekken 4 (PS2) stage is four archive files, and the biggest is a 15-section container holding the geometry, textures, floor, walls, crowd and start positions. The geometry and wall formats rebuild the stock stages byte for byte, and a new stage 17, with its own geometry, textures, props and collision, loads and plays in PCSX2.
Rev. B - QL-0017
Part 5: How large can a Tekken 4 stage be? Bigger than predicted
A desk model of Tekken 4’s stage memory predicted the game would fail once a stage’s main file passed about 7.6 MB. In PCSX2, stages of 6.0, 6.6, 7.4 and 7.7 MB all loaded and played: the game gave up its pose cache and then shrank a second buffer instead of failing. The same run confirmed the crowd budget and the start-region mechanism.
Rev. A - QL-0018
Part 6: Tekken 4 ignores a wall whose faces wind against their normal
A custom wall in a Tekken 4 (PS2) stage only blocks fighters if each face’s corners wind so that (c1 − c0) × (c2 − c0) points the same way as the face’s stored normal. A correctly placed wall wound the other way loads, links into the collision grid, and is walked straight through. All 867 stock wall faces follow the rule.
Rev. B - QL-0019
Part 7: Tekken 4’s character models, and editing them in place
Tekken 4 (PS2) fighters are CHRTK4 models: VIF packets of skinned vertices and textured strips that the PS2’s vector unit consumes directly. The format is decoded well enough to reshape a head, widen a body and build a 3D beard out of hidden hair meshes, all at the original size, and the results render in PCSX2. Adding new vertices or bones is still out of reach.
Rev. A - QL-0020
Part 8: Tekken 4’s sound system, from the hidden driver to the music tables
Tekken 4 (PS2) hides its sound driver inside the executable as a compressed, bit-inverted package; the project unpacks and repacks it, and the repacked driver runs identically. The banks, the sound-effect tables, the music track tables and the stage-to-music map are decoded, and music swaps, shortened tracks and replaced sound banks all work in PCSX2. Every result was read from memory: nothing has been checked by ear.
Rev. B - QL-0021
Part 9: Testing a PS2 game with no one at the controller
How the Tekken 4 project proves changes in game without a person playing: PCSX2 is booted by script, steered with synthetic key presses, and asked for savestates, which hold all 32 MB of main memory plus sound and video memory. Every in-game result in the project was produced this way, with rules learned from the times it went wrong.
Rev. A