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Street Fighter 2 for 8-bit systems

Posted: Thu Jul 11, 2019 5:04 pm
by Wall_Axe
I keep thinking it would be cool to get a disassembly of the arcade machine and then basically just translate the game mechanics and gameplay over, (ie hitboxes,jumping dynamics etc.)
then translate that into the correct bitcode for each system
Then create very small sprites to represent the characters so that the whole game could fit into 128k or 64kb on the C64 or whatever the limit is on the master system

Re: Street Fighter 2 for 8-bit systems

Posted: Thu Jul 11, 2019 8:12 pm
by Ralf
Easier said than done :)

I was personally interested in Street Fighter 2 code at some moment. And it looks that there isn't any documented disassembly anywhere. I guess people are afraid of copyright stuff. So the only documented code is probably only on some old diskettes stored in some rusty Japanese safe ;)

And even if we had nicely documented code which we could understand it would be still a mammoth work to convert it to 8 bits. I guess it uses a lot of hardware tricks which would be just unavailable on Spectrum.

At some moment I also tried to understand the logic used in Zx Spectrum version. As you may know Speccy version sucks. The graphics are okay but the gameplay is terrible. Not only it's very slow but also quite unpredictable. You have just one fire button so you completely have no idea if your hero punches, kicks, makes special attack or whatever when you press it. The instructions are also infamous here. They give some info for let's say Amiga version and while loading you are told that Spectrum version differs from manual so all this info is useless :twisted:

Unfurtunately my disassembly skills turned out too weak to understand it. Maybe one day I'll make another attempt.

Re: Street Fighter 2 for 8-bit systems

Posted: Thu Jul 11, 2019 9:25 pm
by Wall_Axe
someone has done a disassembly of the sf2 arcade and translated most of it to C
i guess that could be translated to z80. it would be funny to see the exact arcade gameplay of sf2 on a spectrum :D

a disassembly of spectrum sf2 would be interesting. I guess they had to reverse engineer the arcade game and build it from scratch so that explains a few things.

Re: Street Fighter 2 for 8-bit systems

Posted: Thu Jul 11, 2019 11:11 pm
by Sokurah
Wall_Axe wrote: Thu Jul 11, 2019 9:25 pm a disassembly of spectrum sf2 would be interesting. I guess they had to reverse engineer the arcade game and build it from scratch so that explains a few things.
I think I can safely say that they didn't reverse engineer anything and "just" coded the whole thing from scratch.

There probably isn't all that much actual "game code" in the game btw. Lots of graphics and lookup tables that hold information about what to do when something is hit. I bet it's all quite simple.

Re: Street Fighter 2 for 8-bit systems

Posted: Fri Jul 12, 2019 10:01 am
by Ralf
someone has done a disassembly of the sf2 arcade and translated most of it to C
You probably mean this guy:
https://sf2platinum.wordpress.com/2015/ ... d-warrior/

As you may see he's afraid of copyrights, he has something but he won't show it:
Since I can’t likely share my source or binary without infringing Capcom’s copyright, I decided I should at least start a blog to share with the world what I’ve found from the code, for whatever reason you might be interested.

I’ll likely never be able to release my full code or binary, so I want to share as much of my findings as I (legally) can so if for some reason I can’t continue, not too much of this goes to waste.


But you can read his entire blog, there is some fragmentary info about SF2:
https://sf2platinum.wordpress.com/

EDIT: and it looks like he started but he didn't finish

Re: Street Fighter 2 for 8-bit systems

Posted: Sat Jul 13, 2019 11:12 am
by toot_toot
When you think about it, Street Fighter II isn’t really all that different from Yie Ar Kung Fu. There are different stages with different fighters associated with those stages and each of those fighters have different “Special moves” (although they are weapons based than various appendages being expanded out!) Theres also energy bars and the ability to do ridiculous jumps over your opponent!

There are some limitations of Yie At Kung Fu, only having two locations and the screens didn’t scroll..... but... the Spectrum conversion was a pretty good game and I think if the style of Yie Ar Kung Fu was updated to make more of the 128k memory, it could have worked as a template for Street Fighter II on the Spectrum.

1) Have the ability to choose different fighters, instead of just one in Yie Ar Kung Fu
2) Change the current 9 fighters to those in Street Fighter II
3) Increase the backgrounds (and therefore the locations) from 2 to 9 (should have been possible with the 128k!)

I did find the “press space” to swap between ping and kick a bit of a pain, so I would just limit the number of moves to a select few, similar to IK+, meaning from you only had to use one button.

Of course it would be radically different to Street Fighter II and at the time would probably have been derided when compared to the SNES conversion, but it could have been a much more enjoyable game. Arcade conversions that played to the Spectrum’s strengths (and sometimes made design decisions by removing certain features or enhancing others) always seemed to be more enjoyable, especially when going back to them now!

(Although the irony is that Yie Ar Kung Fu on the 128k Spectrum really didn’t make the most of the extra memory!)

Re: Street Fighter 2 for 8-bit systems

Posted: Sat Jul 13, 2019 12:31 pm
by Ralf
True. Street Fighter 2 is a big brother of Yie Ar Kung Fu. The Way of the Exploding Fist is similar too although it basically has only one type of opponent which works both as player and enemy.

And meanwhile there was also first Street Fighter which exists on Spectrum too but unfortunately was nothing special both at arcades
and home machines.

SF2 was a great hit not because it was original but because it was much better than everything made before. It has a great, very well tuned gameplay, lots of different attacks and techniques and possiblity of choosing different characters gives a lot of replay value. It started some hype for one on one beatemups and hundreds of clones were made.

Speaking of something similar to Yie Ar Kung Fu, Russian coders made their version of Mortal Kombat with small sprites and not scrolling screen:
https://spectrumcomputing.co.uk/index.p ... 6&id=12965

Image

There were also other attempts of MAing Mortal Kombat but this one is the only one completed. It's okay, I guess. It works, you can play it but for me it wasn't even 50% as fun as big commercial fighters. Unfortunately the details matter here a lot and making a good AI is harder than most people believe.

It isn't any big science, neural networks, advanced algorythms and so on. It's just a proper set of parameters, actions and behaviours but setting it right probably requires hundreds of hours of testing and adjusting.