Reverse engineering Street Fighter 2

[Satsui Ryu]

Not sure if this has been posted before, but I found an interesting blog from a guy who worked on reverse engineering Street Fighter 2. He didn't finish from what I see on the blog, but it gives some pretty cool insight into how the game was built, especially the AI. It confirms much of what you can observe when playing the game like the computer reads controller inputs and the computer does not need to go through the motions of doing special moves.

https://sf2platinum.wordpress.com

Even though some great fighting games came out around that time, this shows a huge flaw that came with playing the computer of those games in that it was less about developing an effective playing style than it was exploiting the holes in the predetermined logic from the developers.

 

[facePuncher7]

Not sure if this has been posted before, but I found an interesting blog from a guy who worked on reverse engineering Street Fighter 2. He didn't finish from what I see on the blog, but it gives some pretty cool insight into how the game was built, especially the AI. It confirms much of what you can observe when playing the game like the computer reads controller inputs and the computer does not need to go through the motions of doing special moves.

https://sf2platinum.wordpress.com

Even though some great fighting games came out around that time, this shows a huge flaw that came with playing the computer of those games in that it was less about developing an effective playing style than it was exploiting the holes in the predetermined logic from the developers.

Interested in reading!

Believe it or not I've tried to find original Street Fighter 2 source code before, and this will probably be quite enlightening for me.

 

[cabear]

definitely interesting, i wish he had gotten farther with it.

 

[Satsui Ryu]

Interested in reading!

Believe it or not I've tried to find original Street Fighter 2 source code before, and this will probably be quite enlightening for me.

Me too. Most of those old games were made with like assembly code and I was always curious at how their code looked compared to modern coding languages. But good luck getting a hold of something like SF2 source code legally. Best you can do is like this guy and hack the ROMs.

 

[facePuncher7]

Me too. Most of those old games were made with like assembly code and I was always curious at how their code looked compared to modern coding languages. But good luck getting a hold of something like SF2 source code legally. Best you can do is like this guy and hack the ROMs.

Seems like an enormous undertaking. I code for a living but never touch assembly level instructions, so it was a very cool read.

I found it interesting that the AI was largely constructed of pre-defined short patterns. Certainly dont remember it having that feel back in the day. Maybe if i were to pick it up again having that knowledge it would be noticable.

 

[Satsui Ryu]

Seems like an enormous undertaking. I code for a living but never touch assembly level instructions, so it was a very cool read.

I found it interesting that the AI was largely constructed of pre-defined short patterns. Certainly dont remember it having that feel back in the day. Maybe if i were to pick it up again having that knowledge it would be noticable.

Yeah I could only imagine the tedium of thinking of and coding the actions and reactions for every potential scenario.

When I first played SF2, I could kind of see that the computer had some set patterns, but it wasn't ultra apparent. Things like Ken would just keep Dragon Punching without even being close to the player. I've been playing a lot of the 30th Anniversary and I am more cognizant of it. And at least SF2 didn't rely so heavily on reading player input like MK2 did where the whole AI seemed to be built around reacting with impossible timing to player input.

 

[SwamiLeoni]

Cool find. I like this quote.

For some moves, such as E.Honda’s Hundred-Hand-Slap, Chun-Li’s Thousand-Foot-Kick, etc. the AI scripts include a couple of moves to make it look like they are subject to the same rules as human input (and also a clue to new players how to execute the moves), but the AI machine is capable of launching into any power move as easily and instantly as any ordinary attack.

Gief still couldn’t stop the neutral jp.hk cheese though.

 

[Satsui Ryu]

Cool find. I like this quote.



Gief still couldn’t stop the neutral jp.hk cheese though.

Its amazing how prevalent this technique was in the game. It seemed like it worked on any version of the game at any difficulty. You'd think some programmer would've taken the time to give Gief a better way to react to that.

 

[SwamiLeoni]

Its amazing how prevalent this technique was in the game. It seemed like it worked on any version of the game at any difficulty. You'd think some programmer would've taken the time to give Gief a better way to react to that.

A simple lariat with invincibility frames would have handled that. I wonder if there were any invincibility frames in the game. Maybe just a DP?

 

[Crimson Fury]

Its amazing how prevalent this technique was in the game. It seemed like it worked on any version of the game at any difficulty. You'd think some programmer would've taken the time to give Gief a better way to react to that.

Try ST which has the cheapest AI in all of the versions of SF2 and in any SF game. The characters reacted to your inputs like in MK2 including Gief.

 

[Satsui Ryu]

Try ST which has the cheapest AI in all of the versions of SF2 and in any SF game. The characters reacted to your inputs like in MK2 including Gief.

I've been playing it on the 30th Anniversary and yes it is brutally cheap. It feels like the new characters are especially cheap. It makes it so the game is almost unplayable unless you enjoy simply spamming exploits in the AI.

 

[Crimson Fury]

I've been playing it on the 30th Anniversary and yes it is brutally cheap. It feels like the new characters are especially cheap. It makes it so the game is almost unplayable unless you enjoy simply spamming exploits in the AI.

That's how old games were. They were there to take your quarters. To be honest, compare to some of those SNK fighters in the past, ST isn't that bad at all.

 

[Satsui Ryu]

That's how old games were. They were there to take your quarters. To be honest, compare to some of those SNK fighters in the past, ST isn't that bad at all.

They were kind of all over the place with challenge for those games. The first few iterations of SF were not terribly hard, but with ST and the X-Men game that came out around that time they cranked the challenge up to 11. Then from there they dialed it back a lot with the Alpha series and Marvel games. They made those games almost too easy.