"This isn't just like a port to a new platform," XCOM: Enemy Unknown designer Jake Solomon tells me over the phone. "From a development angle, this is one of the - and I honestly can't think of another experience except for The Walking Dead - where it's a game, a AAA game that we just put out on consoles, and we're putting the whole thing out to tablet. This is something that I can't take any design credit for, but turn-based strategy games work really well on mobile devices. It's sort of a happy accident, in that sense."

The project can be traced back to the time when Firaxis was finishing up its work on XCOM: Enemy Unknown for PC and consoles. 2K China presented a version of the game running on iOS, and from there Firaxis would work with them on the portable incarnation due this summer. It features the full functionality seen on other platforms, thanks to the Unreal foundation that has played nice with iOS since late 2010.

"Without Unreal, it certainly wouldn't have been possible," Solomon says.