Hacking the RF Protocol of an Obscure Handheld Game


When you think of old-school handheld games, you probably picture something like Nintendo’s Game Boy line or the Sega Game Gear. But outside of these now-iconic systems, there was a vast subculture of bizarre handheld games vying for a slice of a teenager’s weekly allowance. Many of them were legitimately terrible and frankly not worth remembering, but a few offered unique features that were arguably ahead of their time.

One such game was Hasbro’s short-lived POX. As explained by [Zachary Ennenga]the game didn’t spend much time on store shelves as its core concept of defeating undetectable alien invaders bent on destroying our way of life proved more than a little problematic when it launched in September 2001. That’s not to say it didn’t have some cool ideas, like a wireless ad-hoc multiplayer capability that lets your game autonomously fight other units that have come close.

Fascinated by this feature film since his youth, [Zach] set out to investigate how this relatively inexpensive kid’s toy was able to do this when even flagship handheld consoles still used physical link cables for multiplayer. He was aided in his quest by a particularly helpful patent, which not only gave him clues to the frequency, data rate, modulation and encoding of the RF signal, but even explained the logic and overall structure. Much of what was in the document seemed like wishful thinking on Hasbro’s part, but reading the marketing pitch still revealed some salient technical details.

A decoded POX packet.

Armed with an RTL-SDR, GNU Radio, Inspectrum and a bit of Python, [Zach] was able to identify the signal and begin the decoding process. This is where things get really interesting, as the details of its reverse engineering process are broadly applicable to all sorts of unknown RF signals. Even if you’re like most people and have almost no interest in failed handheld games from the early 2000s, it’s worth a read. The same techniques he uses to determine the name and physical characteristics of the invisible enemy his game transmits could one day help you figure out how to manipulate data from that wireless weather station you have in the backyard.

Once he understands the main parts of the protocol, [Zach] moves on to creating its own packets and broadcasting them in a way that the real hardware recognizes it. He even offers a code that will automatically fight games that roam within range of his Yardstick One, which may come in handy during the inevitable POX Revival.

While that might seem like a lot of effort to put into a game that most people have never heard of, we’ll remind you that some of the greatest hacks to ever grace these pages were born out of similar activities. Even if you are the only person in the world who directly benefits from your current line of research and experimentation, there are still plenty of like-minded people in this community who are all happy to cheer you on from the fringes.


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