I want to write a story about a group of people playing Augmented Reality (AR) games in a city that similar to any city we have in the modern world. A game like the one in the new anime movie Sword Art Online: Ordinal Scale, or something like Pokemon Go if you haven't watched that movie before. The problem is that I want it to be a game with money reward (the money are from advertisement and sponsor, more or less like cash price in eSports)

GPS is not a good solution, as you can see how easy it is to fake GPS location in Pokemon Go. In the Sword Art Online movie, it was solved by having small drones flying around the city to locate the players, where I doubt if any city would allow that legally, not to mention that would be very expensive.

So, are there there more secure way to report location for a AR games?

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    $\begingroup$ @ArtisticPhoenix Please don't post answers in the comments section. Comments are for requesting clarification or suggesting improvements, not for answering. See the placeholder text when you click "add a comment". $\endgroup$ – a CVn Mar 8 '18 at 7:14
  • $\begingroup$ Have you seen the movie "Call Up" imdb.com/title/tt3923388 It was a pretty good augmented reality game flick. $\endgroup$ – ArtisticPhoenix Mar 8 '18 at 8:05
  • $\begingroup$ Is this a massive multiplayer game where people must use their own device? Or is using a custom device a possible answer? $\endgroup$ – Erik Mar 8 '18 at 9:28
  • $\begingroup$ @Erik, if it is necessary in tracking the location, you may set it to a must. Else, I prefer not to force the user to do so to make room for story. $\endgroup$ – cytsunny Mar 8 '18 at 9:39
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    $\begingroup$ This seems like an XY Problem. The question is about un-spoofable location, but the real problem seems to be about detecting or preventing simple cheating at the game. Lots of ways, both location-related and not, to do that. $\endgroup$ – user535733 Mar 8 '18 at 13:13

Realistically, they'd use multiple factors. Deriving location from multiple independent sources is always better than any single solution however neat.

Some suggestions:

GPS Practically free, so there is absolutely no reason to use it.

Celltowers and Wifi Gives independent verification that the phone is in the area reported by the GPS.

Mesh networking The player devices can probably connect to each other. This is a useful addition since the players move. This means the set of connections a cheater needs to spoof is constantly changing and it would be difficult to control which devices are close to you reliably.

Player cameras AR devices need to see the environment. This includes other players. This means the game will get a constant stream of random identity and position checks. This would make cheating risky unless you can control all the players in the area.

Surveillance cameras Cities are filled with surveillance cameras. If the game can hook into this system it can see all players in many areas. And the game will know in advance where it can observe the players. By putting all critical targets in areas that the game can see or that require players to move thru areas the game can see, the difficulty of cheating goes up drastically.

Required actions The game can require players to perform verification actions. AR devices are likely to have some biometric verification capability at least as good as with smartphones. The game can require actions that the surveillance cameras ot other players can see and verify. A player observing an action by another player acts as a verification on both players.

Environment modelling The game can recognize what the players see and verify it matches what other players and cameras have seen. This can include changing elements such as cars, people, or weather which can be difficult to spoof over time, if the game has independent data sources.

Behauvior modelling The game can build models of how players act. This allows it to spot player characteristic actions to support positive identification and suspicious actions or patterns that trigger added verification by the system.

By combining these and other data the game should be able to verify player location and identity with high confidence. More importantly, the more factors the game uses the more difficult the system will be reliably to spoof. If your GPS says you are in a location where a surveillance camera sees nothing, the game will not be fooled by your GPS. If your location data suggests you can teleport or walk thru the walls the system will not trust it. If you see a red car when other players see an empty parking lot the system will not trust your video.

  • $\begingroup$ On the "Required Actions" front, you could have NFC points that change code according to a function of time - so long as the function and seed values are unknown, players would have to physically visit the check-in points, and the check-in points could also report back that they are being used. Tie it into something like "free public transport for players", or to access certain locations, or even have them as mana/ammo/health recharge points so that Users need or want to check in regulary, but can't access the device to spoof it. $\endgroup$ – Chronocidal Mar 8 '18 at 11:38
  • $\begingroup$ +1. Enunciates far better my answer than I ever could! $\endgroup$ – Miller86 Mar 8 '18 at 14:21

Radio direction finding from cell towers. That's how the police could triangulate on phones before GPS became ubiquitous.

Two not-big-deal issues:

  1. The cell phone companies would need to be involved.
  2. Real-line RDF isn't as near as accurate as GPS. Many towers and technobabble would make it very accurate.


A radio direction finder (RDF) is a device for finding the direction, or bearing, to a radio source. The act of measuring the direction is known as radio direction finding or sometimes simply direction finding (DF). Using two or more measurements from different locations, the location of an unknown transmitter can be determined; alternately, using two or more measurements of known transmitters, the location of a vehicle can be determined. RDF is widely used as a radio navigation system, especially with boats and aircraft.

The cell towers are known locations. RDF from multiple (not just two) towers triangulates the location of the phone built into your AR headset.

  • $\begingroup$ Adding to this: two angles, each from a known location, gets you the intersection of two circles, but there are multiple possible solutions to that, not least of which if you can't tell the distances involved. Three angles each from a known location will tell you which solution (position) is correct. GPS uses fundamentally the same principle but needs four satellite transmitters since it's working in three dimensions. More than this number will give you better accuracy and/or shorter time to position fix, but isn't required mathematically. $\endgroup$ – a CVn Mar 8 '18 at 7:19
  • $\begingroup$ This still doesn't seem to be able to tell whether it is a real person holding the phone or it is fastened to a drone that moves around in the city and the player is sitting home and operating their phone remotely. $\endgroup$ – Real Subtle Mar 8 '18 at 8:21
  • $\begingroup$ @RealSubtle that's probably why SAO:OS went with drones. $\endgroup$ – RonJohn Mar 8 '18 at 13:36
  • $\begingroup$ @MichaelKjörling right. I mentioned having more than two towers in the last paragraph. $\endgroup$ – RonJohn Mar 8 '18 at 13:37

I left a comment to another answer but then it was starting to turn into an answer. So I'm copying it here and continuing the thread:

Using only the phone, you won't be able to tell whether it is a real person holding the phone or it is fastened to a drone that moves around in the city and the player is sitting home and operating their phone remotely. Maybe additionally, you could make pictures with the phone's front camera and see whether it is a person holding it but that could be faked by gluing a picture there. Voice commands can probably be issued from the remote location and don't identify the player.

I can't see a way around a means of identification that doesn't rely on the phone itself. So maybe install check points with cameras and a sort of handshake protocol with the phone itself. It would be expensive to install them, though, and probably unrealistic if you're developing this game on your own. Unless you got permission to piggyback on already existing systems.

ETA: I just thought of another way: real world communication between players: your players get instructions to meet other players who are close according to the GPS. When they meet up, they exchange sort of passwords: both players get a keyword or something on their phone and they give it to the other and the other player types it into their phone. This confirms that both players were at the location their GPS said they are and both were humans actually playing the game. To prevent two or more people from cheating by only meeting with each other this way, you give a bonus to players who meet someone they haven't encountered before and give only a diminishing percentage of the points if two people have met before (depending on how many times they met in the past x weeks.) This would be a lot cheaper.


You need multiple systems.

Firstly, for location spoofing, you could use a combination of the GPS and radio location systems already discussed. If they disagree, they go with whatever's considered more accurate for that specific case. It's a lot harder to spoof two systems than one. You could roll this into other methods - occasional NFC/RFID tags to be read, QR codes to scan, 2FA passwords (hat tip real subtle), or even if there are other players "scoring" at the same time and location, group selfie!

Another concern - not being attached to the phone- is quite simply covered- have the phone request photos randomly when points are awarded. If it can't take the photo, no points are awarded and you must take a photo the next time you "score". Miss two in a row and you start losing points until you do take a photo with you in it. Face recognition tech exists already for this to work. Your winners have their history audited against similar photos. Any photos without their face in it, that don't match other photos taken at the same time, or could've been doctored= no prize!


Watch them.

film noir being followed


A time tested way to keep track of another person: have someone watch that person. A watcher who is good at seeing and not being seen. If this is for a fiction, it would be a great way to inject the story with a contrasting human energy that has deep roots in pretech thrillers.

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    $\begingroup$ ...if OP does go down this route, please have them wear something other than a trenchcoat and a fedora. Maybe even ideally change attire from time to time. $\endgroup$ – a CVn Mar 8 '18 at 14:48
  • $\begingroup$ This is a good method to watch one small group of person, but for a game with large user base, this is not a very good method. $\endgroup$ – cytsunny Mar 9 '18 at 3:04

Crowd source your player location burdens by offering incentives to non-players who document the location of each player using their cell-phone cameras. Supplement these observer contributed sightings with the feeds from traffic-cams, police-car-cams and public webcams.

There is a movie which used this idea, but I can't recall its name right now.

  • $\begingroup$ Sounds like the GDR to me, and the legion of Stazi informants. $\endgroup$ – RonJohn Mar 8 '18 at 6:51
  • $\begingroup$ You could create a block chain for it.... lol $\endgroup$ – ArtisticPhoenix Mar 8 '18 at 8:03

You could use RFID chips.

One dawback is you would have to plant receivers all over the city. This is sort of a double edged deal. A. you have to plant the receivers, but B. because they are your receivers you control the network. So it's almost a necessary evil.

Even this, though, is not fool proof. The reason the GPS has an issue is not because of GPS its because of the public nature of the data. So even with RFID someone could hack your system and use it to tell were someone is.


These are used at stores to keep stuff from walking off, and I've seen them used at hospitals too, especially on the "baby" floor to keep tabs on the location of newborns.

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    $\begingroup$ Not only planting the receiver, maintenance is also needed. Also, it is hard to prevent people from stealing / destroying the RFID chips. I think the cost is cheaper than drones, but still not economically possible. $\endgroup$ – cytsunny Mar 8 '18 at 7:50
  • $\begingroup$ True, I was just trying to think of something not mentioned. $\endgroup$ – ArtisticPhoenix Mar 8 '18 at 8:04

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