It existed and was too fucking expensive for what it did and how it worked even in the terms of mechanical keyboard connoisseurs. (It was mechanical, but to cut some costs they used the worst Cherry switches they could lay their hands on.)

Still, it could be praised as a proof of concept that such things were doable. I hear there's a kickstarter on a keyboard with Eink screens, which is reportedly not as hideous.

The Lebedev studio also produced an Optimus Mini Six macro pad which was more useful and lived a bit longer after the Maximus bit the dust.