Analysis of Yakuza 5 Hack Videos

I happen to be pretty hyped over the upcoming US release of Yakuza 5 — I’m a big fan of the series’ odd mix of ridiculous melodrama, wide variety of activities and minigames, and really satisfying combat. So naturally, after the localization was announced, I went around looking for videos of the game to watch. First off, I found this amazingly comprehensive and lovingly-assembled survey of the whole series — it’s not really related to the rest of this post, but if you’ve never seen these games it’s worth watching to get a glimpse of how unique they are, and what’s so appealing about them to me.

Then, I found some videos of some hacks that someone apparently made to the game, to allow the player to play as Haruka and another female character (Mai — no idea what her place in the story is). During the normal story arc, there is a chapter where you play as Haruka — however, her fights are rhythm games and dance battles, not the sort of bare-knuckle brawls for which the series is famous. This hack instead allows you to play as these characters during other chapters of the game, where you engage in tons and tons of fistfights. And, somewhat surprisingly, if you watch the videos, it looks pretty good!

So, putting on my ex-game developer hat, what do these videos tell us about the way the game is built, and why this was possible? And is adding a new playable character to the game as simple as these videos make it seem? Here are some of my observations and speculation on how this works, and its limitations.

  • The female and male characters must be animated using the same skeleton. Basically, because all of the combat animations that these characters are using are the same ones that the standard playable characters use, Haruka and Mai must be built and animated on the same basic skeletons as Kiryu, Saejima, Akiyama, and Shinada. This is a little surprising to me, but it goes a long way to explaining why the female characters in this series always seem to…uh, have a somewhat mannish feel to them. I’m guessing that, for the original PS2 games, that this was done to save memory, and then brought forward because it worked well enough and making unique skeletons would require duplicating an already-large animation set.
  • Haruka and Mai are missing a lot of animation metadata. The most obvious case is when Haruka goes to light up a relaxing cigarette after beating the tar out of countless schlubs, just like uncle Kiryu.
  • The smoke from the cigarette comes out of Haruka’s chest — or, more accurately, the origin (0, 0, 0) of the character. There’s a missing animation attachment point in Haruka’s metadata, and the game engine falls back to the origin. Interestingly, Mai seems to have this attachment point — the smoke appears in the correct place for her.

    Another example of missing metadata is this HEAT attack with a bowling ball — it pops away from Haruka’s hand and looks like it’s stuck on her nose. And if you freeze-frame a similar HEAT attack with a beer bottle, you can see that the bottle looks like it’s stuck on her lips.

    I believe there are also missing camera focus points — for example, at the end of this HEAT move, the camera seems to be focused on the origin point of Haruka, and her face is off camera. If I remember correctly, this move looks different when performed by one of the other player characters — the camera tracks the head and it’s in the frame.

  • They’re also missing a lot of animations. The easiest case to spot is that Haruka and Mai’s faces remain completely expressionless, and possibly unblinking, during fights — they don’t have any combat “barks” (voice + facial animation), and they don’t play any reaction or pain facial animations as they lay waste to their foes. While it kind of lends a comic tone to the video, this would definitely not be acceptable for an officially supported character. It just looks strange.
  • The game’s IK seems to work OK with these characters. I had kind of assumed that the engine supported IK, given that a lot of the close combat grabs in the game look pretty good. When Haruka grabs a thug by the hand, that’s a pretty strong signal to me that they’re doing some limited IK, because if they weren’t, you would probably see a gap in the throw animation as Haruka’s character is physically smaller than, say, Kiryu’s. Another example of this is Mai kicking the sign stuck on a thug’s head — it’s just too unlikely that it would look good without IK support.

    Note that there are still some cases where it looks like they don’t normally use IK, and just rely on the animations fitting the sizes of the characters — Haruka lifting up a thug looks pretty bad, as her hand is nowhere near the thug’s chest.

  • Haruka and Mai’s hair is not built to be animated during combat. In the case of Mai, her hair basically doesn’t move at all. And Haruka’s hair physics object was clearly conditioned to look good during movement animations, but not tuned at all for anything that would look like combat, with its frequent flips, tumbles, falls, and dashes. It’s all over the place constantly.
  • Both characters seem to be using Akiyama’s move set. But I can’t tell if this is just a convenience, a deliberate stylistic choice on the part of the author, or that none of the others would work. I think it would be kind of funny to see them using Saejima’s brawling moves, though.
  • Surprisingly, there was no content protection on the game assets. Presumably the author of these videos was able to simply pull out the PS3 HDD, and modify the files directly on the hard drive to point a character definition to Haruka or Mai’s models. It’s a little surprising to me that these were left unprotected, but perhaps Japan has less societal anxiety about hot coffee than the US. Maybe I should have a look at the installed data, to see if I can verify any of my conjecture here.

In closing, I think these are really neat, fun videos to watch, and that it would be very cool if female characters in future Yakuza installments were able to fight and brawl. But there are enough rough edges and missing content in this hack, that it should be clear that making them fully playable is not just a matter of flipping a switch (or deciding to change the story) and suddenly having Haruka powerbombing fools alongside her uncle Kiryu. There’s a lot of missing content and additional polish that would need to go into making Haruka and Mai fully first-class fighting characters in the game.

Questions or comments on my analysis are welcome!

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