In a recent tweet, Kojima talked a bit about the difficulties of designing the controls for a game.
Changing control function(button) as differs b/w Japanese&Westerner.Also differs the sense of touch depending on the hardware. Difficult.
— HIDEO_KOJIMA (@HIDEO_KOJIMA_EN) September 3, 2013
As many fans will remember, the older Metal Gear Solid games used the circle button for confirmation, and the x button to cancel – which is uncommon in Western game design, but common in Japanese games. Different controller designs for different platforms is another factor. These are the kind of things that make it difficult to design a game for multiple audiences.
It’s not really clear whether he’s talking about Metal Gear Solid V, or something else, but it would be the most logical assumption he is.
Kojima also posted a photo, with the description ‘in studio now’. He didn’t detail what he was doing in said studio, though.
Source: Hideo Kojima Twitter