[REQUEST/SEARCHING]: Global location-based wargame

Hi! This is my first topic here. If I have posted in the wrong category, please direct me somewhere else.

I am looking for an iPhone game like the one described below. I had the idea last night and thought it seemed pretty cool. If there isn't one, could someone please create it?

(FYI: I tried Shadow Cities, but interface and action-oriented combat didn't really cut it for me.)

General description

I've been thinking about a global location-based map-like game application. It's like an MMO in the aspect that you can create and rule your own guild/team, but you make use of so-called "command posts" to battle other players.

These command posts are scattered across the globe, maybe points of interests or just random places added by the players. Could be as little as 200-300 metres between them. You and your team capture these command posts and try to hold them against other teams, as well as capture the command posts of your enemy. As you capture CP's, you gain Credits. These Credits can be used to fortify your own CP's so that they are harder to take over.

Taking over a command post requires you to walk to the specific location and perform a task. There could be "regular" command posts (or guard towers, if the game is in an augmented medieval settings, which would be awesome) which only require you to stand near the post's coordinates, and click "Capture" on your phone. There could also be special command posts, which require you to complete a task (like, the stronghold is password protected and you need to go somewhere else to find out the password). Or the gates of a stronghold are only "open" at a certain time, e.g. 5pm, so you have to be there right then to capture it. The thing is, the defending team might have sent someone there to defend it.

If two players from different teams meet at a command post, some kind of battle system would kick in. (Nothing physically dangerous, maybe rock-paper-scissors or something more imaginative). Players could also use Credits to spawn guards/monsters which the ones conquering the CP would have to defeat.

It's not a flawless idea, but I think it would be great fun. The only location-based game I have played so far is Geocaching, and while it allows for sight-seeing and lots of exercise and fresh air, it doesn't always require you to work together and there's no real competition. It would be great fun to expand your dominion with some friends, recruit more people and finally control the entire town.

Thoughts? Thanks for reading.