To achieve the visuals Square demonstrated in its impressive Luminous Engine demo shown last month, next-generation consoles will need an ample serving of RAM. That's according to Square's creative director and senior manager Takeshi Nozue, who told Edge (via TSC) recently that "memory size is the biggest challenge" to any hardware hoping to achieve that level graphical fidelity.The textures in the demo, Nozue explained, are of such high detail that their sheer size puts a strain on system memory. The demo ran on a high-end PC packing Nvidia's beastly GTX 680, and Sony and Microsoft's consoles will need to cough up serious figures to keep up with it. Square is confident, at least, that PS4 and Xbox 720 will "come to a level of quality that will support". It's perhaps not quite so confident that the Blu-ray disc format will be up to the job of storing a next-gen game on a single disc.