Copyright pcgamer
In 1997, two young hobbyists released two pieces of software that more or less prompted a new wave of interest in "retro" games—which were, at that point, really just a few years old. The first punch was Nesticle, a Nintendo Entertainment System emulator that quite suddenly made it free and easy to play Nintendo's '80s and early '90s games on a PC. The second punch, delivered near the end of the year, was ZSNES, which did the same for much newer Super Nintendo games. And it was fast—even on the modest PCs of the era. "When I was 16 years old I started learning assembly, and I got so fascinated with optimization, making everything as fast as possible," said zsKnight, the developer behind ZSNES, in an interview last week. While most software is written in higher level programming languages like C++ that are easier to work with, even at a young age zsKnight was skilled enough in low level assembly language to start using it to program his own emulator. Back in 1997, computer processors weren't yet fast enough to accurately emulate game consoles. While the Super Nintendo's 3.58MHz CPU was much slower and simpler than, say, a 133 MHz Intel Pentium CPU, every operation the console performs every fraction of a second has to be interpreted and then rewritten for the PC's processor, which isn't nearly as efficient. zsKnight recalled trying an early SNES emulator called Super Pasofami, which ran at about 10 fps on his PC and didn't even support sound. He wondered if he could do better. "I started coding everything in pure assembly—until the Windows port there was not a single line of C code in there," he said. "It's optimized to the brim. When I first started it, I wanted a Super Nintendo emulator that could play at full speed on my computer, but I actually did not expect to meet that goal." As far as I'm aware this is the first time zsKnight has done an interview about his time working on ZSNES (other than this brief article from 2001), and it's quite a sweet retrospective. He's speaking with the creator of Zophar's Domain, one of the earliest emulation fan sites, and delves both into the creation of the emulator as well as what he did after leaving the project in 2001. He didn't know how incredibly popular ZSNES was until he interviewed for a job at game publisher EA—they were all impressed by his work on the emulator. And for good reason, as this video from Modern Vintage Gamer helps summarize; ZSNES really was amazing in its day. Outside work, though, few people ever knew who zsKnight was. "When we released the first version of ZSNES, the friend who told me about Super Pasofami was so excited about ZSNES. He told me 'there's this awesome emulator out there!' I kept my identity a secret; I told him those guys who made it must be pretty amazing people, and he said 'hell yeah!' To this day he doesn't know it's me. I kept the development of ZSNES and my real life separate." My favorite bits of the interview touch on ZSNES's iconic snowy effect when you open the UI. Despite being burned into the memories of a whole generation of emulation fans, it was basically a lark. "It's a thing I only spent like an hour working on. I think people just love Easter eggs, and it looks nice… you're in this menu and it just feels peaceful." Most interesting from a technical perspective, though, is how zsKnight got online multiplayer working in the emulator on the dial-up connections of 1997—basically inventing his own version of rollback netcode decades before it would be commonplace in fighting games. "30 times a second, I do a secret save state. The emulator plays ahead, maybe 30 milliseconds, and whenever it gets a packet saying the controller has changed, it rewinds to that frame and replays the emulation until the current point with that new input buffer." After spending years in big budget game development, zsKnight actually released his own indie game this year called Retro Endurance 8bit, a WarioWare-inspired collection of about 50 minigames. While the minigames were originally designed to just be played for a few seconds, during early access he's been expanding on them, and now 20 of them can be played as multi-stage arcade games. Even if they're simple, that's a lotta game for the $4 it costs on Steam.
