Cromfel echoed the debate that is happening out there as to whether implementations are really AR or not and how making comparisons is challenging.
Thats how you can interpret the situation if you perceive the AR from its legacy point of view. My opinion being that such question as "Is Google Glass AR or not" is simply wrong question. I would apreciate if you took the time and watch the youtube lecture. It looks long but I encourage you to watch it
In classical sense, where you can pose such questions, you see Augmented Reality in every game already. User interface is contextualized information perfect example of it is TF2 with Oculus rift and how "ARish" the UI actually is (The UI elements in such case are that of Google Glass type and fall under abstract reasoning). Take for example Battlefield 3 and start to analyze what is going on when you play. Your squad members are being overlaid with graphical indicators that are spatially correct and give you enhanced awareness (This is now concrete reasoning AR, where your spatial and temporal parts of brains are tapped into even if the name tags for example are abstract, the main added value is of the spatial reasoning). That is Augmented Reality in Virtual environment right there, in two different games representing 2 of the modalities.
This very thing allows for example me to use Virtual Reality to prototype Augmented Reality applications without developing any real technology. Thats right, for our industrial VR/AR applications we use virtual reality to prototype real systems, for example product or even virtual reality systems themselves (For example use of HMD to evaluate powerwall / cavesetups) and use of VR to prototype any kind of AR application you can imagine without bothering yet with technical development and risking that your application is not actually useful. Mind boggling? No not really. People have just technology oriented fascination and hype on AR without bothering to too much understand what is actually going on with VR and AR.
If you want to create augmented reality game, it would mean that your perception of reality is augmented with synthetic stimuli for the purpose of entertainment. Where as this stimuli would be of gaming nature. Be it solving some kind of puzzle, compete for scoring etc. I suppose you are augmenting visual perception. Now, what kind of game you want the player to experience?
Lets say you wanted to create augmented reality MUD? Google glass would be sufficient for that. You capture the basic components of what makes a good MUD and incorporate the physical presence in specific location to your gameplay. Incorporate google maps to it or whatever. And you make the action as just text based adventure. Future of LARP? Anyway, thats tapping to your abstract reasoning whereas your physical presence at specific spot gives you context. Game content is purely based on your abstract reasoning while being contextualized with concrete reasoning. No, Im not any kind of MUD expert just using it as example to widen the mindset.
Now, I suppose we stick with so called classic AR with overlaying graphical content to real world. Such as 3D objects, say monsters etc, one needs such device that have optical see through (very challenging) or video see through. Google Glass or Meta 1 and such devices will not do. They are still too primitive for the task. Say you had Oculus rift and 2 HD cameras that could provide you with video see through. Then you combine it with some tracking solution like ALVAR from VTT or Metaio pick whatever. Now you can start to overlay graphical content to your field of view s there was monsters crawling etc. Thats pure concrete reasoning right there while you are running away from the zombies that haunt you on the streets. Watch out for reality while you are at it. Dont be fooled by the nice technology demos you see like Meta1 etc. They are appealing only for the audience and not for the user itself. They use optical see through without any benefit of the see through capability. It is even counter intuitive actually due technology limitations. Its exactly same effect what allowed Johnny Lee to demonstrate head tracking. That is tapping to your concrete reasoning even when the medium is normal display. FOr the actual user the AR demos on those videos is not actually delivered. Thats still on the dreaming state.
What I want you to understand that Augmented Reality as technology will not be giving you much cues what kind of game is fun or meaningful or engaging. First of all you must envision the game and what kind of gameplay you want to achieve. Then you go and pick the relevant technology to implement it and be totally objective what you actually want to achieve with your technology. Some games could be just fine with smartphone providing you with the graphics overlay while the GPS and other sensors provide you with contextualization in case you plan to make some geo-tag game. Some games could actually use your visual sense to be overlaid in Oculus Rift kind of way so that you feel immersed by the monsters.
Thats the downside of VR & AR at large. They allow you to do everything. Yes, I mean it, everything you can imagine. But the technology will not make up the lack of meaningful content. Understand your medium. Pick your target audience and then develope a game that respects the medium and the audience. This is for example the reason why "true VR" claim of Oculus rift falls short. The wide field of view is not any more or less VR than some old z800 HMD. In given application the z800 is perfectly fine. It is not about technology when it comes to VR/AR. Sure, good tech widens your scope and gives you higher propability to succeed with your application. (DOnt get me wrong, I love rift Its awesome!)
I feel almost dirty to try make people to see the lecture and try to understand it, maybe over time it will happen. It may be all confusing at large but I promise that you will appreciate understanding these things when you actually want use AR outside of dreaming and hype scenarios, and you are trying to figure out what is exactly the added value of AR in your game.
Historical reasons are what they are and they derail a lot of attention from us, humans, and our perception of reality. Technology is the enabler for us to do all those fancy and nice tricks, but its nothing but technology that we try to harness for specific purposes. When it boils down to design of systems that deliver you ought to understand for what purpose you use what set of technologies. Its not easy for sure, been there done that, failed many times among few successful systems.
We are only starting to get slight understanding what AR actually is, no matter how many experts you see, with perfect confidence, telling you about head mounted displays and floating 3D objects etc. I make a bold claim that these people simply dont know in full widht what they are dealing with ;)