Shenmue (1999) reverse engineering reveals possible sun position oversight

https://wulinshu.com/2025/03/11/reverse-engineering-adventures-3-bug-or-not-bug/

by BafS • 1 year ago

183 81 1 year ago

Man I loved this game so much as a kid. I remember being enthralled by opening the drawers, lol. I basically played it once a year every year from ages 9 - 16. Some of the enchantment was lost when I played the remaster recently, but still such a great world they built.

AlecSchueler• 1 year ago

What didn't work about the remaster or was it just a matter of shattering the illusion of your memories?

I've been thinking about the game a lot since having my first child last year. She often lifts things and rotates them in her hand just to see and experience them. When I was a kid playing Shenmue I always found it funny that they added that mechanic because "who does that?" but now I feel a very deep appreciation for it.

yoyohello132• 1 year ago

What didn't work about the remaster or was it just a matter of shattering the illusion of your memories?

At the time it was a unique, first of it's kind, game. Now there have been a lot of advancements since then so I didn't have the same "Wow" feelings of just being in the world. But the nostalgia still hit me hard and it still has a special place in my heart.

soupfordummies4• 1 year ago

An all-timer for me as well! So much strange magic in there. No game before or sense has quite that vibe. Maybe a product of it coming out at just the right time.

"Do you remember... that day?"

"The day it snowed?"

NO! The day I got it right as it came out. A Friday after school and I played for like 4 hours straight. Yes! I remember THAT day!

WXLCKNO• 1 year ago

There was something very special about it, I agree that no game has made me feel that way since.

Half Life 2 did but in a different way.

Maybe when a game just leapfrogs what's been thought of as cutting edge and you're so amazed that you forget that you're playing a game.

I'm not sure if my fascination for Japan started with Shenmue but it certainly grew from there. I was so happy to visit for the first time last year.

mywittyname2• 1 year ago

I traded a bunch of PSX games for a Dreamcast just so I could play Shenmue. My parents were pissed, but what a great game (and great console).

VBprogrammer• 1 year ago

I remember driving a forklift for hours!

fredrikholm2• 1 year ago

Me and my friend completed the game together as kids, and I vividly remember us being stuck at this stage looking for sailors (IIRC).

It accidentally imbued a lot class awareness into us; all we wanted was to revenge our father but here we were, driving boxes around hours and hours being paid pennies.

byproxy• 1 year ago

Same! So satisfying to just explore the world they built, to the point of me neglecting the actual story a lot of the time. Hell, I think the only reason I advanced the story was to unlock new dialog from the NPCs. I loved the whackiness of 'em.

Unfortunately, I think the lost enchantment is just a product of aging. Things I were so enthusiastic about as a child (videogames, particularly) no longer have the same appeal, despite my best efforts to reignite some passion. That said, I did put in a good chunk of playtime with the remaster and I was still having fun with it. Though, not to completion as my attention span for videogames has dwindled.

fredrikholm2• 1 year ago

It was so extremely ahead of its time.

A seemingly unlimited amount of content, nearly everything could be interacted with, and the graphics were very good compared to other games in 1999. Heck, the y had teeth meshes.

The background music for nearly every environment lives rent free in my head some 20-odd years later.

AdmiralAsshat• 1 year ago

Reminds me of a similar story about Blast Corps, specifically how they implemented logic to correctly display apparent retrograde motion vis-a-vis the orbit of Venus from the perspective of Earth...all just for what basically amounts to a background animation. [0]

[0] https://www.youtube.com/watch?v=FZ6eNJi02Qk

soupfordummies4• 1 year ago

Well that's ANOTHER oddball, semi-forgotten, great game!

toast0• 1 year ago

Nintendo and Rare (as "Xbox Game Studios") figured out how to work together, and as of Feb 2024, you can play Blast Corps on the Nintendo Switch Online Expansion Pack (along with a bunch of other Rare games)

rawling• 1 year ago

Isn't this just... they made the planets have the correct orbit times, and retrograde motion just drops out from that?

gs17• 1 year ago

Yeah, it's impressive that they bothered to animate them with the correct ratio of periods, but it's not like they had to add epicycles.

QuercusMax2• 1 year ago

When I took the sophomore-level Computer Graphics class as an undergrad in 2001, the final project was to build a solar system simulator in OpenGL. It didn't have to be especially faithful (all orbits perfectly round, don't care about starting positions, etc). The most complicated part was implementing a view from a planet's surface which would rotate at the proper rate for the given planet. This was not a difficult assignment (for me, can't say anything about my classmates!).

Making it marginally more accurate for a real product would only have been a bit more effort.

klysm• 1 year ago

This is one of those things where it's like if you have to program them to move, it's probably just easiest to program it to be somewhat faithful instead of making up some other values.

mywittyname2• 1 year ago

To me it feels like one of those escapades we go on when we want to focus on doing some "fun" work.

pipes• 1 year ago

Someone in the YouTube comments claims he was an intern at rare at the time and he was responsible for this. Who knows, they could be lying.

wk_end• 1 year ago

The tl;dr (though you should read!) of the "oversight" is that there's a constant used to adjust the sun's position that's seemingly based on latitude; in the first Shenmue, it's set to 22, and in Shenmue II - which uses much of the same code - it's set to 35. This is odd, because Shenmue I takes place at latitude 35°, and Shenmue II at 22° - precisely the other way around.

If that's what's going on, it's sort of hard for me to wrap my brain around how that might've happened. I could see them "fixing" the Shenmue I code base and then forgetting to "unfix" it for Shenmue II, but I can't - even knowing that there were already plans for where the sequel would be set - come up with a story for how they would've accidentally used Shenmue II's latitude for the original game.

chickenzzzzu• 1 year ago

Maybe the code was written at the early onset of the game, and originally the locations were flip flopped in super early development. Then later they decided on the locations that became permanent, and nobody bothered to fix that part of the code?

mook• 1 year ago

Maybe they realized the bug early in Shenmue II's planning and decided to just move the game to where the bugged value was correct, not knowing that it was fixed in code in the mean time.

(This has an approximately zero chance of being correct.)

boudin• 1 year ago

I wonder if it could be linked to the original development on the Sega Saturn, if I remember well the video of the prototype, Shenmue on Saturn was spanning across both Shenmue 1 and 2

ac2u3• 1 year ago

I wonder if it has anything to do with the default cutscene that plays on the start screen if you don’t progress. That cutscene would have been set in China as its Shenhua reciting the games central prophecy

gpderetta• 1 year ago

Wild guess: they set it wrong on the first game (possibly by looking up the wrong parameter). On the next game, when they went to fix the sun position for the new location they realized the mistake and changed it to the original location as an easter egg.

The coincidence of the wrong position matching the location of the next game is strange though.

bbayles• 1 year ago

Fantastic game!

The same development studio, Sega AM2, recently had a developer reveal that he had put an Easter egg into Fighters Megamix for Saturn. However, he mistakenly introduced a crash bug in it.

This set me off looking for the Easter egg. After a couple days of reverse engineering, I finally found it [0]! I love looking for this stuff.

[0] https://32bits.substack.com/p/bonus-fighters-megamix

kowlo• 1 year ago

What a game. Lost hours to QTE Title (one of the games within the game) https://www.youtube.com/watch?v=drdFhBKDvIQ

chiffre01• 1 year ago

Playing through Shenmue 1, they did a really good job capturing the vibe of the area. Looking at random points in Yokosuka just feel like Shenmue.

https://www.google.com/maps/@35.2781594,139.677597,3a,75y,27...

soupfordummies4• 1 year ago

Looks like a good spot to practice my moves...

If you google "Shenmue locations in real life" there's a lot of cool stuff. They really did do a great job on that and the ERA as well.

pkdpic3• 1 year ago

Also playing through on Steam Deck. Steam QTE problems really haven't hindered my enjoyment at all. Kind of shocking how well it's aged overall and how different it is playing through as an adult.

I am waaay better at driving that forklift 20+ years later. The foreman loves me now.

drooopy• 1 year ago

I replayed Shenmue on my Deck about a year ago and I had the same QTE problems. The solution was to download a custom, community-made control scheme from the Steam workshop.

jncfhnb• 1 year ago

I too discovered that the forklift was in fact very easy as an adult. That was a shocker.

pandemic_region• 1 year ago

Is it typical for Japanese towns to have all the electricity wiring above ground? Is it on purpose, maybe related to historical earthquake trauma?

Daz1• 1 year ago

Yes and also there is zero aesthetic thought put into japanese towns which is why they're so ugly, everything is functional

lmm3• 1 year ago

Is it typical for Japanese towns to have all the electricity wiring above ground?

Yes

Is it on purpose

Yes? Electrical wiring is built deliberately, of course it's on purpose. Where else would you put it, and why? You're implying it's somehow normal to bury it? That sounds like it would be expensive, both to build and to maintain.

pezezin2• 1 year ago

Pretty much all Japanese cities look like that.

dfxm122• 1 year ago

Hasn't changed much since 1986, either. Speaking of Sega games set in Japan, the Yakuza games do a good job at this as well, at least for Kabukicho and Dotonbori. I even knew to get crabs at Kani Doraku because of the games! It's like virtual tourism in some ways...

indrora• 1 year ago

A friend of mine through sheer luck happened to be able to take a two month trip to Yokosuka nearly all expenses paid. She spent the first week or so just plotting out the map of Shenmue and the local map to see how much was rearranged.

The town is definitely Different but recognizable in a lot of ways. Lots of small landmarks that were gently adjusted or changed to make it simpler

bitbasher• 1 year ago

Ok, but do they know who Lan Di is?

TapamN2• 1 year ago

Shenmue is one of my favorite games. I did a bunch of Ghidra reversing on the Dreamcast version last year, since I wanted to add improvements to it. Like adding bilinear filtering on the sky background, making time run a bit (faster so you can see time specific events like Christmas/New Year more easily,) getting the game to run without disc swapping on an ODE, and adding antialiasing (which would require mipmaps to improve rendering performance, which would require higher texture compression levels to get them to fit, which would require a different texture format that supports that...) I never got around to actually implementing any of that, outside of doing some experiments, like forcing bilinear on all 2D elements.

I don't think I found the sun/moon code (or more likely I did, but didn't realize what exactly it was doing, Ghidra SH4 has serious problems with floating point instructions making following anything that uses them almost impossible) but I did find most of the other time related code for updating the clock/calendar.

One weird thing I found while doing that is about the in-game watch. You always have a watch in your inventory, so you'd think it would be hard coded in, but it's treated like any other item. The game also has code to check if the watch is missing and add it back in anyways. But the code that draws the on-screen clock also checks if you don't have the watch, and won't draw the clock if you don't have it (or at least part of the UI clock logic is disabled, I haven't actually tried seeing what happens if you don't have a watch to verify if my interpretation is correct).

On the PAL version, the code that checks for a missing watch is at 0x0c180dc6 (that's where the code is loaded into memory, subtract 0xc010000 to get the address in 1ST_READ.BIN), and I think the code for drawing the clock (or at maybe it was just updating the hands of the clock?) is at 0x0c18290a.

Dreamcast Shenmue has code to support other video modes, like alternate resolutions (320x240p!), antialiasing, and 24/32 bit color. They're a bit bugged, like when using antialiasing, the 2D elements being squashed into the left half of the screen, and some strange issue with the screen position for the RAMDAC being setting incorrectly, causing the screen to vibrate left/right by a pixel or two, but the 3D models were drawn correctly.

24-bit color worked surprisingly well (even if the flag intended to enable it didn't seem to work, and I had to force it elsewhere.) I would have thought that having less video RAM free would have caused serious problems, but the game just loaded fewer NPCs. It was strange playing without dithering.

makotech221• 1 year ago

wouldn't using an emualtor allow you to do most of that stuff

TapamN2• 1 year ago

Some of it, but I'd rather use real hardware.

ac2u3• 1 year ago

Is it true that lucky hit in Shenmue 2 used historical weather data so that humidity had an effect on the wooden pegs on the board?

NooneAtAll3• 1 year ago

I wish the article spent 2 sentences introducing wtf Shenmue is

donatj• 1 year ago

It's a game, for Dreamcast. Certified classic. Amazing technical demo for the time. Redefined what games could be. The Yakuza games would not exist without it and are generally considered it's spiritual successors.

Shenmue was one of the first 3D games where realistic human characters had details like individually movable fingers. It was a very big deal for the year it came out.

qingcharles• 1 year ago

My all-time favorite game. What's the best version to play these days?

billfruit• 1 year ago

While not Shenmue, Yakuza:Like a Dragon: Infinite Wealth, released in 2024 has got good reviews.

pkdpic3• 1 year ago

Playing it on Steam Deck right now. Only issue is with QTEs but honestly hasn't bothered me at all. Thought that might ruin it. Overall it has been an excellent way to replay it so far.

ghostly_s• 1 year ago

I’m not sure a single person in this thread actually read the article rather than just taking an opportunity to say how much they like the game.

I read it and I’m not sure I get the point—it seems in the end what they discovered is the simulated sun position in the first two games are based on each other's locations. Not familiar enough with the series to understand what implication that has, but in any case, is it an easter egg or an oversight? It can't be both.

denz88• 1 year ago

The first game is set in Yokosuka, Japan, which has its latitude at 35deg north. The second game is set in Hong Kong, which has its latitude at 22deg north. It seems like whoever coded this data into the games may have swapped them.

regus2• 1 year ago

I was really hyped for Shenmue when it came out on the Dreamcast, but I wasn't crazy about it once I finally played it. It was a glorified point and click adventure game, and it ultimately had no ending or purpose. It was an interesting and ambitious idea for a game though, they threw the kitchen sink in there.

My favorite part of the game was playing space harrier in the arcade.

ascagnel_• 1 year ago

While it's not a direct continuation, the Yakuza (and later Like a Dragon) series is a spiritual successor in some ways.

isthisfoss• 1 year ago

I really hate this analogy. Yes it's also published by Sega but the director, development team, and gameplay elements are quite different. Shenmue to me was mainly about NPC interaction and open-world exploration whereas Yakuza is just a straight brawler re-intepreting classic Yakuza tropes.

The move from Shenmue I to Shenmue II almost makes me think that was the direction Yu Suzuki was heading but never really ended up there. Have not played Shenmue III yet so I could be wrong.

tt_dev• 1 year ago

Didn't read the article but man do I love this game.

Ros2• 1 year ago

The moon in-game also has a complex implementation. I don't think anyone realized this until the team porting the games to modern consoles pointed it out in an interview

https://www.phantomriverstone.com/2020/09/ryo-goes-to-moon-s...

mtillman• 1 year ago

I read every piece of US magazine coverage during the development of this game until finally 3-4 years later I bought my Dreamcast on launch and eventually Shenmue followed by a boot disc and Shenmue 2 (UK). 6 years of waiting to spend countless hours playing Space Harrier and Pachinko not to mention find some sailors. Absolutely loved this game.

pkdpic3• 1 year ago

I just coincidentally found my old dreamcast while cleaning out my dad's storage space... Guess I'll be buying some batteries for my VMU...

Also excellent write up and discovery, truly inspiring *clap_emoji *bow_emoji

nanna• 1 year ago

Shenmue I and II will stay with me forever. I waited and waited for Shenmue III, and swore that when it came out I would buy whatever it took to play it, but the reviews were so poor that I haven't even tried it. Is it worth it?

ac2u3• 1 year ago

Haven't yet completed it. In my opinion, although the originals had a clunky control scheme, it still had charm. Really bugs me how they moved the camera to an "over one shoulder" view rather than directly behind like in the first games. (nitpick) They also changed the iconic font used in the for no good reason.

dfxm122• 1 year ago

Shenmue is in a unique genre. The gameplay of III is more of the same, but not very innovative on top of what came before it. So, if you like I & II, you'll probably like III. The game plays as if it came out in 2003, not 2019, if that makes sense, but it takes full advantage of the graphics capabilities of the PS4. I understand mixed reviews. If you did enjoy I & II, the gameplay feels nostalgic & familiar, and you've probably played nothing like it in the past 20+ years. If you didn't, the gameplay probably seems antiquated, if not quaint, and you understand why there aren't many games like it.

My qualms with the game were more story related.

Rendello• 1 year ago

I can't say from personal experience, but I did find this review by Dunkey hilarious and likely representative of the gameplay: https://www.youtube.com/watch?v=f7SVY9CyBBc

khaki54• 1 year ago

Imagine being proud of yourself for 25 years, displaying "implemented innovative orbital positioning methodology for Shenmue" on your resume. It was even your promotion case for staff engineer since you did it yourself, and some guy comes by more than 2 decades later and points out that you actually did it wrong

Shenmue (1999) reverse engineering reveals possible sun position oversight

Related Stories