I would love to see a game that took elements from the Achtung Panzer games, the Hearts of Iron series and the Arma series. It could belong to an entirely new genre, let's call it Massively Multiplayer Online Real Time Grand Strategy Military Simulation First Person Tactical Shooter Role Playing Games. MMORTGSMSFPTSRPG's
There would be a tier of players focusing on the political and economic aspects controlling and guiding nation states as they do in HoI
A second tier of players would organise and control the military forces of these nations, overseeing strategic implementation of the politicians global policy as they do in AP
A 3rd tier would be able to control individual soldiers/airmen etc within those armies, from platoon commander down to individual grunt as they do in Arma, with an emphasis on roleplay and realism as practised by the Shacktac community for example.
All game modes are entirely interlinked and it's set in WW2 of course.
What would be your ideal game or blend of games if you could invent a new genre?