How Street Fighter II's Computer Opponents Cheat To Kick Your Arse

Screenshot: Desk

Have you ever plopped a quarter in the Street Fighter II machine at your local pizza joint and readied up with your favourite character, only to find yourself bashed and bloodied by the CPU just a few rounds later? Perhaps you said something to yourself about the computer cheating, only to get heckled by your friends. Well, according to this YouTube video, it totally was.

Combo expert Desk recently took a rest from breaking fighting games to highlight the ways in which CPU characters cheat in the various arcade incarnations of Street Fighter II.

These underhanded tactics include becoming completely invincible for short periods of time, which allows them to interrupt attacks that are normally safe. Desk demonstrates this with side-by-side footage of the same situation being played against the CPU and a human to show just how devious the arcade mode opponents can be.

Let’s say you manage to hit the CPU with enough attacks to stun it. Time for free damage, right? Wrong. Street Fighter II allows CPU opponents to escape the dizzy state in just 12 frames, or 1/5 of a second at 60 frames per second.

This is incredibly fast and, to the best of my knowledge, it’s a speed that’s impossible for a human to pull off even with optimal execution. In effect, it’s a little like the rubber-banding tactics seen on the part of AI opponents in games like Mario Kart.

The last bit of Desk’s video covers how the CPU can perform charge and mashing moves — like Guile’s Flash Kick and Chun-Li’s Lightning Legs, respectively — without the requisite inputs. This means Guile can simply walk forward and Flash Kick whenever he wants, forgoing the down charge necessary to pull off the move as a human. Sometimes, the CPU even fakes like it’s charging to give the impression that it’s totally above board.

Much of the info cited in this video comes courtesy of blogger sf2platinum, who has spent years digging through the Street Fighter II code. One post in particular details the AI engine, explaining the game’s unsophisticated methods of turning the CPU into a decent sparring opponent. Give that a look in between frustrating rounds of getting screwed out of your quarters.


Comments

    The CPU dizzy thing was a pretty common 90's fighting game trait for Arcade Mode. Also, the charge characters all had reduced input time as CPUs after Vega became playable. The computer did cheat all along! It became obvious after mutliple play-throughs that the CPU had access to mechanics a human player would not.

    I'd still like to know if the "CPU gives you a chance" after multiple continues though. Sometimes in SFII, you'd struggle with a fight and be stuck continuing repeatedly, then this one opportunity to bash the shit out of the opponent comes out of nowhere.

      I like to think that the planets align for just a moment that allow me to triumph in a RL display of anime tropes.

      I have seen games advertise lower difficulty when you suck too much. Back in Darkstalkers 1 I started to main Morrigan because I couldn’t beat her.

    It was pretty common in fighting games particularly in the 90s to do stuff like this. I played the 2D Mortal Kombat games a lot and the CPU blatantly cheated in those games too.

    Everything from being able to throw you mid move that would normally hit a human player, and even if you were correctly throw blocking (holding down+away+block together meant you couldn't be thrown, but the AI ignored it and could throw you anyway), to being able to sweep you from well outside sweep distance, to being able to execute charge moves (where you need to hold a button down for x seconds then release) in rapid succession that a human would not be capable of, to being able to execute moves that require back inputs (eg. back, back, high punch) while continuously moving forwards (normally a human would need to stop moving forwards, even if only briefly, in order to execute a move that required back inputs, but the AI ain't got no time for that).

    It also just simply liked to button read you like a mofo and react with inhuman speed to whatever inputs you made.

    MK1 and MK2 were relentless, but starting from MK3, the AI eased off after you'd taken a few losses, giving you more of a chance to beat them and progress to the next opponent who would subsequently have the AI cranked back up to 11 to kick your butt again.

      Check out some MK1 and 2 vids. Mk was horrendous for cheating. Basically it was designed to autoblock almost every shot you threw and only allow in a certain percentage.

        I just said the AI cheated lol, I don't need to check out vids, I played them enough to know that.

          Might wanna tone down the passive aggressiveness? I was just pointing out how it did it? O_o

            Sorry I didn't intend for that post to sound passive aggressive.

    This makes me feel great about that ONE single damn time I managed to actually fight Akuma. Did it once but never ever again. I think I about had a heart attack when I finally got to him.

    No not "Sheng Long" :P those stories around the schoolyard though were hilarious :)

    Nice to see confirmation after all this time and that it wasn't just an excuse my 10 yr old self made to save face.

    That said, I can totally understand the AI not actually having to register the input buttons to activate a move. With storage being so limited, it would really just be an act of efficiency in the code to simply call the function of a move directly as opposed to literally activating multiple button presses to make an AI perform the move.

    I remember playing SSIITNCs in SNES. The game in its hardest setting cheated blatantly, doing things that were impossible for a human player like diagonal spinning kicks for Ryu and Ken or connecting special moves before the animation finished. It was like "HADOU-HADOU-HADOU-SHOOO-SHOOORYKEN!"

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