A furious former Xbox engineer and co-founder has blasted Microsoft for letting down gamers, developers and investors with 'five years of failure'.

Nat Brown was one of the leading engineers of the original Xbox team, and even came up with the name.

And by most measures, the Xbox has been a huge success. The latest generation of the machine has now sold 76 million units, while Xbox Live has 46 million paying subscribers.

But now on the eve of a new generation of Xbox machines, Brown has let loose at his former employer in a vitriolic blog post titled 'Stupid, Stupid xBox'.

"Microsoft has jumped its own shark and is out stomping through the weeds," he said.

"Their home town is on fire, their soldiers, their developers, are tired and deserting, and their supply-lines are broken."

Brown contends that Microsoft has squandered its massive installed user base, passionate fans and broad content platform.

He argues that a failure to innovate, and unwillingness to allow developers to easily make and sell games on the device, has given Apple, Google and Valve an obvious advantage. Their relatively open app stores stand in stark contrast to the awkward deals and approval process developers have to go through to have their games show up on Xbox.

"Why can’t I write a game for xBox tomorrow using $100 worth of tools and my existing Windows laptop and test it on my home xBox or at my friends’ houses? Why can’t I then distribute it digitally in a decent online store, give up a 30% cut and strike it rich if it’s a great game, like I can for Android, for iPhone, or for iPad?"

He adds that the Xbox OS is "creaky, slow, and full-of-shit", with confusing menus, frequent bugs and an obtuse membership program.

And with the still-unannounced next generation Xbox already attracting criticism for reportedly requiring constant internet access, no second-hand games or backwards compatibility with old titles, he suggests the future is bleak.

"The past 5 years, and the last year in particular, have been simply painful to watch. Coasting on past momentum. Failing to innovate and failing to capitalize on innovations like Kinect. Touting strategic and market success when you’re just experiencing your competitor’s stumbling failure (yes, Sony, Nintendo – you are, I’m afraid, stumbling failures). A complete lack of tactical versus strategic understanding of the long game of the living room.

While admitting that the plan for the Xbox was always to go beyond games and offer movies, TV, music and apps in the living room, Brown says Microsoft is pursuing deals with "big dying media companies" ahead of its audience's true needs.

Brown concludes that Apple is now Microsoft's most insidious competitor in gaming, even though its Apple TV product doesn't yet play games, because players - and developers - have move to mobile games on the iPad and iPhone.

"I see big investments in future interactive content happening, as well as idiotic moves to limit used games or put harder content protection into place than exists in mobile or tablets – i predict massive failure and losses here," he says.

"xBox just needs somebody with a brain and focus to get the product in order tactically before romping forward to continue the long-term strategic promise of an xBox in every living room, connected to every screen."