Ever wanted to play Tetris on a giant computer that takes up your living room? Chances are the answer is “no,” but you may change your mind when you see the computer that British tinkerer James Newman built in his house. The machine has lights that let you actually see the computer working through sums.

Newman built what he calls the “megaprocessor” in his house in Cambridge. This was no Sunday afternoon whim: the machine cost nearly £40,000 to build (over $53,000), weighs a staggering half ton (with solder accounting for almost 5 kilograms, or 11 pounds), and measures 10 metres long (over 32 feet) by 2 metres tall (over 6 feet).

Why? In his own words, “because I want to.” Newman started keeping a diary of his process back in October 2014, with the project finally completed on June 22, 2016.

Instead of using tiny transistors like traditional computers, Newman used larger, discrete ones. He then attached LEDs to show visually what was taking place during each calculation. In total, the machine has around 10,000 LEDs and 40,000 transistors.

The result is a processor big enough to actually walk through and watch working.

The megaprocessor can run up to speeds of 8kHz, quite a bit slower than the multi-gigahertz computers of today. Even at these slow speeds, the computer uses around 500 watts of power, largely due to the abundance of LEDs in use.

At the end of his video tutorial, Newman plays a game of Tetris on one of the world’s most interesting machines. Unfortunately, his skills are a bit rusty, but Newman told the BBC that the aim here is to use the machine as an educational tool.

Over the summer, Newman hopes to run a series of open days where members of the public can look at the machine in action. At some point, later on, Newman wants it to sit in either a museum or an educational facility. “I doubt I’ll be able to sell it,” he said.

Photos via Megaprocessor/YouTube