“Where would one begin.”

I'm writing the game server in Go. My first priority is getting an a device to connect to the server and start sending GPS data (over TLS of course :P). Then I will do primitive shape collisions with lines and points, just like a normal 2D game. In fact, the entire game engine is designed like a simple 2D top down game, with the GPS coordinates as player input.

“Are we talking dogbucks or real cash here?”

Virtual cash, for sure. Just for use in-game and maybe to get a t-shirt from me. I'm still thinking of allowing the purchase of points with micro-payments but seeing as how this a resume builder & fun project I'm not sure I want to.

“Am I understanding this right that the aim of the game is to place mines that other players cannot see and get them to walk into them in order to earn a score from the mine. You could put one in a place where nobody can avoid, like the toilet.”

Absolutely. If your Drift is low enough and its in-bounds of the battlefield, anywhere is fair game. I think cross-walks will be great as well, to catch people ridding the bus :) .

“Is there an activation delay when placing mines? What if you put a mine down when you were standing next to each other, they’d get hit immediately.”

That depends on the mine, but the bargain mines will explode even if your in their blast radius! Oh what fun that would be, if both of your phones go off at the same time so you can see your opponent. I was also thinking of using the accelerometer & compass to allow for directed claymores.

“Could be quite interesting the more I think of it. Interesting that you’re actually implementing this, so will have been forced to think through a number of the implementation details inherit to the idea.”

I've thought about this for quite awhile. Basically, this is for casual fun playing, but I could use it as a framework to build a real-time FPS for more hard-core gamers. It's a very fun project to think about.