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I figured I'd bring the conversation on what the ideal WWX app would be from Facebook over to the forums.
WARNING: Wall of text incoming
I think a good place to start would be to look at the existing apps used by various games to see what they do right, what they could add, and what they could improve on.
The Infinity army builder app gets points for not only being able to build an army list, but for containing all the stat information for every unit in the game along with an easily browsable (and searchable!) wiki containing the entirety of the game rules. Corvus Belli also gets points for making the app available not only for mobile devices, but for standard computers as well as a fully-functional army builder website. This may not seem like such a big deal, but having the ability to quickly look up a unit's abilities and rules while either toying with a current list or building a new army from a new faction on the same screen rather than toggling back and forth is a HUGE advantage over everything else. Not only does it make list building less of a chore, but it also makes mapping out future purchases much easier (hint, hint). The ability to export a list either to a file or a specific application code to be opened by another person makes getting list building advice from other players very easy, which in turn helps the community grow overall.
Privateer Press' War Room 2 app has a built-in inventory option as well, giving players the a way to keep track of their models and their basic tabletop status (painted/unpainted). It also does a good job of keeping track of wounds for various units (which doesn't really apply to WWX), but its overall bookkeeping skills are a bit lackluster. I'd like to see better status tracking in War Room 2, but the collection tracker is a nice little feature. It also has the entire ruleset available, though in a standard PDF which can get cumbersome to search through.
The Age of Sigmar app is... meh in comparison to the others. It's basically War Room 2 without the in-game bookkeeping. While it does have the option to purchase new expansion books in-app, the format is rather clunky and not easily searchable.
So what all that being said, what would the ideal WWX app look like?
-Available on as many platforms as possible
-Build posses easily
-Unit information readily available
-Easily searchable rule set (if Warcradle went the wiki route, I'm sure there'd be enough community effort to help maintain a wiki)
-Export saved lists either to file or app code
-Collection tracker/wish list (integrated with WWX web store/forums?)
-In-game bookkeeping (status effects, VPs, etc.)
-Easily accessible books/expansions
One of the things I would stay away from is moving any major game mechanics to the app, such as dice rolls or card draws. Computers really aren't that good at being random, and relying on those may end up skewing enough games to cause some balance issues in the future. I wouldn't mind the option of having dice rolls as a part of it for mathhammering out certain scenarios, but it shouldn't be considered valid for use in regular games and CERTAINLY not in any sort of tournament or organized play.