We've explored what it takes to collect and refurbish existing pinball machines, but what if you want your own, custom game? Creating a one-of-a-kind pinball experience is a much different beast, but we were able to catch up with Wade Krause and Tanio Klyce, two men who put together a special table for some big pinball fans: Metallica.

"[Singer] James Hetfield saw the Hellacopters game that [artist Dirty Donny] and I made a few years ago and he wanted us to build him a custom game," Krause told Ars. That was the genesis of the project, but it takes real ingenuity to take an existing machine and modify it so that both the art and the play matches the feel of a band. Here's how they Krause and Klyce pulled it off.

Start with a good machine

First, "we brainstorm some ideas and find a suitable game," Krause explained. "We wanted a solid state game because of the sound, no dot matrix display because reprogramming it was just not in the budget." They decided to start with a game called Earthshaker.

"The shaker motor was a big plus on Earthshaker," said Krause. "The crowd roars when it is activated. Earthshaker is a fun game as well; playability is a big factor."

The entire game was then sanded, stripped, and refurbished to team member Dan Kramer's specifications, which were described to us as "tighter than factory." Dirty Donny— who in addition to having a great name has done art for Metallica in the past—then hand-painted the playing field before team member Rolph Britain added another layer of clear coat. Extra attention was paid to the back box of the machine, to make the art truly shine.

"The back box is extremely important to me on pinball machines. I am a huge fan of screened line-art on pinball and backglass animation," Krause told Ars. "Donny's art is perfect for pinball. To make the backglass really pop, I doubled the number of lights, added a CNC-cut light baffle board like on old EM games, had to modify the circuit board feeding the lights, and added 12 additional relays for the backbox light features which were programmed by Tanio [Klyce]. The amps glow red at times and the lights strobe METALLICA."

The software is just as important

We know the motor in Earthshaker allowed the game to have the effect of a roaring crowd, but the game had to have sound and music for that effect to have an impact. What good would a Metallica game be without the band's music? That's where Tanio Klyce came in.

"I started by researching the Williams System 11 architecture to learn how the main CPU communicates with the sound hardware," he said. The PinMame project had already reverse-engineered System 11, so he used that source code, a debugger, and the System 11 schematics to plan the music effects. A logic analyzer allowed him to make sure the schematics and emulation matched what was in the physical hardware in the shop.

"We wanted the audio playback to be CD quality (44KHz 16bit stereo), and we wanted to be able to play a lot of different songs, so I chose an embedded Linux system to run the audio," he explained. The other challenge? Pinball games are designed to be played roughly, and the team already had to deal with a shaking play field.

"I prototyped with a BeagleBoard, but moved to a Gumstix Overo Earth board for the final system because it is rated up to 90 C and is reported to have passed the 5 year MIL-STD-810F 514.5 military vibration test," said Klyce.

Here comes the science. "Since the Gumstix Linux board does not use 5 volts on board, I used an Arduino Mega board to interface to the Williams System 11 CPU board. The Arduino Mega watches the sound command signals and translates them into serial commands that are sent to the Linux board over USB."

Custom software on the board interprets the serial commands, keeps track of what's going on in the playfield, and makes sure the voiceovers, music, and crowd sounds all sync up. James Hetfield even recorded some new voice-overs to give the game more atmosphere.

Klyce found that creating sound design for a pinball machine was much harder than he had anticipated, and in many ways was more art than science. After the challenge of making sure the Linux system booted rapidly enough, he played the game for the first time. "My first pass at triggering sounds, voice, and music directly from the sound commands resulted in an unpleasant cacophony," he said. "My initial response was 'Oh, fuck!'"

He then went back and played the game, made notes, tweaked the sound, and repeated the process until things started to sound better. "After a lot of iterations, and a lot of great feedback from Dirty Donny and Wade Krause, the machine's audio now elicits more positive responses, such as 'Fuck, yeah!'"

Where's the machine now?

The game was commissioned by James Hetfield, but he was nice enough to allow the machine to be played at the Pacific Pinball Expo before being set up at Metallica Headquarters. The machine made waves.

A writer from Bit Mob took the machine for a spin. "I'm not sure if it fully comes across in the video, but this table is blisteringly fast—by far the fastest table at the expo. Fancy bump and catch tricks won't work well here. Hell, you're in trouble if you blink," the short review stated. "The color-changing, light-up plunger was a nice touch, as were the numerous songs from a little-known metal band called Metallica. I left the table feeling spent and satisfied, the metal riffs blaring from the speakers still ringing in my ears."

So how much does it cost to put something like this together? Krause gently refuses to talk specifics. "We did have a budget," he says. "Tanio Klyce, Dirty Donny, Dan Kramer, Rolph Brittain and myself put in many extra hours to take this to the next level. I have to say that this is the coolest project I've ever been involved with and thanks to those guys and James for making it happen."