As an example back around April a company called World Inc. started suing major video game companies like Blizzard, regarding patents 8,082,501, 7,493,558, 7,945,856 and 7,181,690 "System and Method for Enabling Users to Interact in a Virtual Space".(original filing, November 1995).

Lawsuit Story

Virtual reality systems to the best of my knowledge were being developed and tested before November 1995(see the guys at VRML - April 1995, but started work in 1994) not to mention many games, although while primitive also used various aspects of what they are claiming. See CitySpace (1993,1994 - SIGGRAPH), various Text Based (MUDS), Wolfenstein 3D(July 1995), Worlds Away(September 1995), Habitat(1986, 1988, 1990, 1994), Neverwinter Nights(1991)

To my eyes their patent claim describes pretty much any 3D multiplayer computer game in which the game is hosted by a central server.

  • So if I understand correctly 0. We think there is a case of prior art 1. But we cannot make a pre issuance submission (6 month time limit after application) 2. So, now we simply step back? Or is it down to blizzard to pay 18k? In detail rule change proposed: inventivestep.files.wordpress.com/2012/01/2011-33811.pdf Clearer write up inventivestep.net/2012/01/05/… Sep 20, 2012 at 22:08
  • You should consider narrowing this down to a specific claim - or at least a specific patent. While obviously all related, these each make slightly different claims, which is pretty important when you're looking for prior art. Putting these all in one question might be biting off a bit too much at once.
    – Shog9
    Sep 21, 2012 at 0:07
  • What about articles found through Netrek; Maze_War (date unclear) and Spasim (1974), both on wikipedia?
    – james
    Sep 21, 2012 at 0:20
  • geeksweep, Also, it is perfectly acceptable to post answers to your own prior art query below. In this case it would probably be preferable. When you continually edit to add more and more "answers" in the space of your question, it doesn't allow other users to vet the prior art suggestions through voting and comments. Add your edits/answers below. Sep 21, 2012 at 0:21
  • Also netrek(as james said)-1988, Lawnmower man(1992)- based on William Gibsons books(1980s), possible Doom(1993)
    – geeksweep
    Sep 21, 2012 at 13:49

14 Answers 14


Providing prior art around the concept (as opposed to alternative implementations) would include the book Snow Crash, published by Neil Stephenson in 1992 - that goes into incredible detail describing several interactions related to a Virtual Space.

  • 4
    Neuromancer by William Gibson from 1984 pretty much coined Cyberspace as a form of Virtual Space/Virtual Reality. The technology described there is rather ahead of ours though.
    – larsivi
    Sep 20, 2012 at 16:55
  • and LawnMower Man (1992) which i added earlier is based on that book. Their claim of "a highly scalable architecture for a three-dimensional graphical, multi-user, interactive virtual world system. In a preferred embodiment a plurality of users interact in the three-dimensional, computer-generated graphical space where each user executes a client process to view a virtual world from the perspective of that user" basically describes everything Gibson talked about and was portrayed about in the movie.
    – geeksweep
    Sep 20, 2012 at 18:46

Examples of online, real-time, interactive, three-dimensional "virtual reality"-type multiplayer interaction in the commercial sector date back to at least 1995; earlier if you count the development time needed prior to the official public release.

Meridian 59 was (is?) one of the first MMOs. It has all attributes I've listed above (online, real-time, interactive, three-dimensional, multiplayer) in their most basic form.

Underlight came three years later in 1998, but I am aware of the fact that very large chunks of the source code comprising this game were copyrighted as early as 1993-1994, and private beta testing with members of the public was available prior to 1998.

I am not sure if text based interfaces would count as prior art, but certainly anything that is even in the same class as MMORPGs (think World of Warcraft, just much more primitive) would have to be legitimate prior art, I think. That said, I have not read the full text of those patents, so more research would be needed to determine whether titles such as Meridian 59 could count as prior art for one or more of the claims in those patents.

  • yeah i forgot about Meridian 59(but the wiki says December of 1995?). I think we could put together a strong case here. Obviously the guys at the patent office were not gamers. To me Neverwinter Nights(1991) is a slam dunk IMO but someone with a keener eye will have to take a look to confirm or not.
    – geeksweep
    Sep 20, 2012 at 16:41
  • i forgot to add that i am sure the development cycle predated the release date of Dec. 1995) so i think that it definitely includes prior art.
    – geeksweep
    Sep 20, 2012 at 16:49
  • Does it have to be published to the general public in order to count as prior art? Sep 20, 2012 at 17:02
  • not totally sure but I would think so. If you were part of an IRC chat room back then everyone was talking about and discussing at length about 3D virtual environments and the latest findings/research of this topic from the private sector. The "obviousness test" fails here in my opinion for the patent holder.
    – geeksweep
    Sep 20, 2012 at 17:13
  • The first multiplayer 3D game I remember was Descent which was released March 17, 1995 Jul 23, 2013 at 10:29

How about prior art in the form of another patent? See: US5899810

I filed this when my company fielded "Terra: Battle for the Outlands" back in the mid-'90s. We came from the distributed simulation world (BBN SIMNET, circa 1983) where nothing was done on a central computer. That worked great over low-latency high-bandwidth connections, but worked lousy over modems. So we moved the "world state" into a central computer. Our patent covers one way to manage that process, such that users perceive less latency than there really is. It sounds a lot like the system described in these patents, and predates them by about 10 years.


xpilot (released in 1991) provides everything as described in the patent except for the 3D aspect.

Is adding another visual dimension sufficiently novel for the purposes of a patent? (apparently not)

An article in the ACM magazine may talk about how it works, but I can't read it you can read it on the wayback machine.

The earliest copy of the XPilot FAQ I can find is from 1995/04/23.

The earliest copy of the XPilot source I can find (not that I've tried much) is from 2001 on sourceforge - too recent.

I'm sure someone has earlier source / documentation lying around…

  • no i don't think so. otherwise everything 3D could have been patented and companies like SGI(Silicon Graphics) could have owned everything related to 3D. In a general sense the idea of going from 2D to 3D isn't innovative or non-obvious. People have been studying different dimensions for eons, so 3D is not some miraculous discovery.
    – geeksweep
    Sep 20, 2012 at 17:19
  • The first patent in the chain doesn't require 3D looking through the site Xpilot definitely seems relevant. Is there any specific documentation of the client server interaction from 1991, or basically before 1995?
    – Plepleus
    Sep 20, 2012 at 17:44
  • 1
    Added links to the main body. While not specific, it looks promising: "In spring 1993, he embarked on something we didn't have the motivation to embark on, but it is perhaps the single most important factor for the game's success as an Internet game. He split the game into two processes, a client and a server."
    – MikeyB
    Sep 20, 2012 at 18:34

While looking through old newsgroups I was able to find this possible prior art:

TwisterGame on Network
by Masaki FUJIHATA, Nobuya Suzuki
Keio University, Faculty of Environmental Information

Aim and condition:

1: Experimentation for connecting 2 different places by an electrical network, using telephone line with modem.

2: A collaboratation in one virtual place where participant will arise through the network. They are remotely connected from their own place. Each participant will share same experience in this virtual place.

3: To examine and construct the rule based framework for sharing an experience.

There was also a presentation at "Networked Reality 1994". Quote from a PDF of the event:

Session 3, was titled Networked Reality Systems and featured three presentations...a networked virtual space implementation of the Twister parlor game, by Fujihata and Suzuki of Keio University.

The networked reality implementation of the Twister game consists of having human operators manipulate, via joysticks, tripedal clones of themselves in a virtual space equipped with a virtual Twister mat. The system was demonstrated on 18 February, 1994 by linking the site of IMAGINA '94 (Monte Carlo, France) with Keio University in Yokohama.

...Twister game presentations had associated demonstration systems available during session breaks.

Problem is that this is probably just peer to peer (modem), not enough detail to tell whether a server is involved.


While founded in 1999, it would be interesting to see some of the prior art that might come from Linden Labs and the founder Philip Rosedale. As I recall when the company was founded it was based off some ideas and projects that had originated from his college days down in San Diego.

However, if we want to discuss some of the earliest prior art that uses virtual reality and user perspective and client/server architecture then I think that Maze War is a very strong candidate. With origins going back to 1973, I believe among other things it was also the first person shooter in existence.

The wikipedia article makes for an interesting read: http://en.wikipedia.org/wiki/Maze_War

While I'm not terribly good at reading patents, looking at the abstract of 8,082,501 seems to perfectly describe Maze Wars as I remember it from my early days at the high school Mac lab.


The old GEnie network offered Air Warrior, a WWII air combat simulator. You could also drive jeeps, parachute from a plane, etc. starting in 1986.

  • 2
    And TheSierraNetwork had Red Baron multiplayer running in 1992/93, which seems to meet all the claims (your avatar just happens to be a plane...)
    – AShelly
    Sep 21, 2012 at 14:07
  • thats a good one. If anything their 4 patents are way too broad to not conflict with prior art as we have listed many. They might get away with '3D avatar" but ill have to do more research in that but that and that alone is not what they are claiming.
    – geeksweep
    Sep 21, 2012 at 15:28

From memory, Doom didn't transmit player coordinates. It transmitted keypresses, and relied on starting up with synchronised random seeds to keep the game in sync between players.

Other games that might be interesting: Spectre VR (1993?) and NetTrek (1984, I think).

How admissible are closed-source games, anyway? Does the publication of an application which uses a technique but doesn't publicly describe it at the time actually count?

  • Your last paragraph sounds like it would make a good question on its own.
    – Adam Lear
    Sep 21, 2012 at 14:34

What about http://en.wikipedia.org/wiki/NetWars

This was bundled with Novell Netware systems. It let 4 players fly around in 3d space and shoot each other.

NetWars was an IPX-based 3D vector-graphics computer game released by Novell in 1993 for DOS to demonstrate NetWare capabilities. It was written by Edward Hill, one of Novell's engineers in its European Development Centre (EDC) in Hungerford, UK. Development had started in 1989.


Swedish Institute of Computer Science developed a virtual avatar-based environment, starting in 1991. The earliest report I can find regarding the work is from 1993: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=


Sierra Online had a Red Barron multi-play 3D flying game.

I remember playing it prior to 1995, so it must date before this filing.

I am unsure if their technology stack required a central server, or if it was peer-to-peer. I do remember you could dogfight multiple users at the same time, over a modem.

  • 1
    It was almost certainly peer-to-peer. Sep 28, 2012 at 15:53

I have a box full of prior art that has been used in several cases like this.

The history of virtual worlds significantly predates Worlds, Inc. - just do searches on "Lucasfilm's Habitat" (1986 video here: http://www.youtube.com/watch?v=VVpulhO3jyc), and a decade later Worlds Away (bogus patent with my name on it here: http://www.google.com/patents/US6476830)

There are several generations of this software during this period, in the US and internationally.


the University Of Washington had a department back in the 80's that was doing extensive research on virtual worlds, head mounted displays, datagloves as input devices etc.. They were one of the pioneers in this field.


The game Midi Maze from 1989 for the Atari ST would have a claim for prior art.

The guys at midimaze.de know a lot more about the gameplay.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .