During the 1980s, it was quite common to see unofficial ports of popular arcade games released on home computer systems. For instance, Acornsoft (the software division of Acorn Computers) released many titles that were clearly unofficial ports (Snapper/Pacman, Meteors/Asteroids, Monsters/Space Panic, etc.).

How did these companies get away with what looks like clear cases of copyright infringement? The legal dispute between Philips and Atari over KC Munchkin shows that companies were prepared to protect their IP in certain circumstances. Was it simply the case that the big arcade companies didn't see the home computer market as a threat, or were there other factors in play?

  • Hardware manufacturers were trying to get as much software as possible for their platforms to increase the hardware sales, most probably not thinking about IP infringement much. But we should not rule out the possibility that original SW developers were involved and were benefiting from these ports. Different names were chosen to distingush between platforms.
    – Anonymous
    Commented Dec 4, 2018 at 14:48
  • There are two versions of Acornsoft Snapper; an original that looks almost exactly like Pacman and a later modification that changes all of the characters — e.g. everyone gets legs. Compare upload.wikimedia.org/wikipedia/en/9/93/Acornsoft-SnapperV1.jpg and static.gamespot.com/uploads/scale_medium/mig/6/3/1/3/… . So someone was likely concerned about some aspect of copyright.
    – Tommy
    Commented Dec 4, 2018 at 15:35
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    @pmarflee Snapper has obviously been on the lam before — though wearing a hat and sunglasses is a more traditional disguise.
    – Tommy
    Commented Dec 4, 2018 at 17:50
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    Even today you see companies ripping off each other's game ideas. It's essentially Zynga's entire business model.
    – user722
    Commented Dec 4, 2018 at 18:37
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    "clearly unofficial ports" - have you looked at the code? Knock-off ≠ Port.
    – Mazura
    Commented Dec 4, 2018 at 22:12

4 Answers 4


To understand what was going on with licensed and unlicensed ports of popular arcade games in the 1980s, you have to understand two critical factors.

  1. The video gaming culture of the time, and the preeminence of coin-op arcade games.
  2. The role of trademarks and legal trademark protections, which was the more crucial law pertaining to arcade game ports at the time.

First off, the rapid growth of home console and computer gaming in the early 1980s was directly associated with the rising popularity of arcades. The arcade experience was the main gaming experience that people (kids, mostly) had prior to this time. And popular arcade games like Space Invaders, Asteroids, Centipede, and (of course) Pac-Man had already captured the attention of kids in every town large & small that had an arcade. The entire promise of the early console/home computer gaming market was in bringing this "arcade experience" into the home, minus the quarters, and preferably with the games that kids already knew and loved. It was distinctly NOT about introducing the public to unfamiliar computer games that had been around academia for over a decade. Those types of games didn't have the market clout of the popular arcade games, and wouldn't convince a mass market to invest in consoles of home computers at the time.

It has been argued by early game console historians, I think quite effectively, that the reason for the early growth of the Atari VCS platform was that Atari delivered a credible, playable, fun port of Space Invaders for the platform. Before that, it was not clear why the mass market would buy into owning a VCS. Space Invaders was immediately recognizable, and the ability to have the same basic arcade experience on a device at home was what sold the mass market.

So, if you wanted to sell a successful home gaming platform at the time, your best marketing advantage was the availability of good quality ports of popular arcade game titles. And, to make this truly effective, you would want the home version of the game to share not just the game play aesthetics, but also the NAME of the arcade title. This is where trademarks, and trademark infringement comes into the focus.

Trademark infringement was already a very-well established legal framework at this time, and was easily applied to arcade game titles. Copyright was not so relevant initially, because software was something new, and it wasn't yet clear how to correctly apply copyright beyond just not being allowed to pass off someone else's source code as your own. The rule for Trademarks is simple: You cannot use someone else's Trademark on your own product, especially when your product purports to be the same thing as the other's product. So, creating a "Space Invaders" video game using that trademarked name (without permission) was out of the question. You would likely be slapped with an injunction from the Trademark owner, and then they would come after you for all your profits from the infringement plus punitive damages. It was simply way too risky and potentially business-destroying to infringe the trademarks of popular arcade games.

This situation begs the question of how to make recognizable, high-quality ports of popular arcade titles available for your budding home gaming platform, given that all such arcade titles were protected by trademarks, and infringing on the trademark was legally untenable. The solution pursued by most publishers (Acorn, Commodore, small third-party) was to make a knock-off of the arcade title instead. Clearly, you could not use the trademarked name for your game, so you made up some new name that sort of sounded related while offering plausible deniability. Then, to farther strengthen your plausible deniability, you changed some details about the games visuals and back-story. The essential game play would remain the same, thus capitalizing on the players' main affinity to the game. So an actual gamer would still recognize the game and want to own it, but the trademark infringement attorneys would have a much harder case to make in court.

This "loophole" was exploited for several years. Some legal claims were made here & there against those trying to exploit the "loophole". Usually these cases were easily settled since neither side had a very strong case and the money involved was usually not much.

At the same time, the larger publishers with the deeper pockets simply struck trademark licensing deals and legally created ports with the same name as the arcade title and with audio/visual content matching as closely as possible. It turned out that these gaming platforms were the most successful. The follow-up was that more makers of arcade games got into the home video game market to offer their own ports. This allowed them to maximize the lifespan and profitability of their IP.

  • 3
    IIRC, it was not just a matter of "ports", it was also a matter of "bootleg" copies. For instance, I clearly remember seeing an arcade game called "Automat" and wondering what the hell that was. At the first image I recognized it as Robocop, but not a "port", the same game with just a different start screen... A bootleg copy. And the list of bootleg games is (was) quite extensive.
    – ChatterOne
    Commented Dec 5, 2018 at 8:15
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    @ChatterOne - bootlegs were a problem back in the day, but from a legal standpoint, they were simple to deal with - like selling a photocopy of a book, they were illegal. The hard bit on that front was finding the manufacturer of the bootleg in order to sue them. Commented Dec 5, 2018 at 15:00

For the most part these games were just not big enough to be noticed or cared about. Acorn computers were mostly sold in the UK and were never as popular as their rivals, for example. If the arcade developers, most of whom were Japanese or American, even knew of those knock-offs they would have had to take legal action in the UK. In the 80s that was even harder than it is today with modern communications.

Atari were more concerned about Munchkin because it was released in their home market (the US) and PacMan was supposed to be their exclusive. The game was for a rival console too, where as Acornsoft's games were for computer systems only.

Also consider that at the time video games were new and courts not familiar with them, and it wasn't even well established that gameplay could be copyrighted in that way. In fact the Munchkin lawsuit established that "look and feel" of software could be subject to copyright, opening the door for other lawsuits in the US.

  • 2
    I never really understood why "look and feel" fell under copyright rather than patent jurisdiction. The wedge-shaped opening in K.C. Munchkin's mouth while it was moving could be construed as sufficiently similar to the shape of Pac Man to represent a copyright or trademark issue. I wonder what would have happened with Tengen's Tetris lawsuit if it had argued that what it licensed from Mirrorsoft was the audiovisual content that Mirrorsoft owned, rather than the "pieces shaped like the seven tetrominos fall from the sky" concept that was not in and of itself copyrightable.
    – supercat
    Commented Dec 4, 2018 at 16:28
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    Trademark infringement was the relevant case law, not copyright or patent.
    – Brian H
    Commented Dec 4, 2018 at 17:58
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    @supercat Because it is not an invention, not a plant, and not the design elements of a functional item, and those are the only three kinds of things you can patent. Commented Dec 4, 2018 at 23:57

From our perspective today, it seems surprising that major companies engaged in wholesale copying of the basic designs of each other's games and only really bothered changing the names of them, but the simple fact is that at the time, it had not been legally determined that such behaviour actually could be copyright infringement. Every country had its own history of judgments, but really the US ones were the ones everyone cared about, and the the idea that the screen layouts and sequences of actions that are what we think of as making a copy of a game feel like the original were actually subject to copyright themselves (as a standalone concept rather than as part of a whole program) wasn't legally tested until the mid 1980s. Whelan vs Jaslow (1986) is generally considered the first real case that supported the idea that such high level user interface details could be subject to copyright. Before that decision, it is likely that game designers never expected the details that were being copied to be legally protectable.


They did it because it was easy! Back in those days there were no microsoft bloatware libraries, a decent programmer could disassemble an entire 10-16k game in under a week and have it ported from any platform to any other. The game was written such that all the code was at the start and the text, images etc neatly grouped at the end so it came apart very easily. We had access to some amazing tools that showed the program flow and within a day you would have all the subroutines mapped out and the basic functionality spread out on your lounge floor. Enough time has probably passed to openly discuss it but back then espionage was rife, I was into systems programming and we pioneered the copying and porting of Atari software (and cracking all their hardware security) making the information and technology 'freely available(ish)', it was not to make money, it was to screw Atari. Nowadays you would go to jail but back then this was how business worked! In those days the programming industry was small, quite often games were ported not by disassembly or copying but by disgruntled employees joining competitors or even disgruntled departments that left and formed their own games company taking with them the entire history, contact list and future R&D on a few floppies, I know it happened to us! Nowadays there's laws, case history, anti-trust, privacy, protection, digital copy-write...

  • 1
    This isn't a great answer... It could be improved by making clearer how it addresses the question.
    – wizzwizz4
    Commented Dec 6, 2018 at 18:28
  • Also pointless 'bloatware' comment, Windows is no different from any other desktop OS in this respect.
    – Alan B
    Commented Oct 9, 2019 at 8:06

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