Lego’s Donkey Kong arcade machine lets Mario jump endless barrels — Miyamoto is reportedly happy

Q: How does the barrel mechanism work, and how many barrels fit inside of it at a time?

The barrel mechanism is essentially a pump. It uses a stack of 14 Barrels going up the side of the model. Each time the barrel lever is pulled, it adds one barrel to the bottom of the stack and one falls out the top. The system holds 20 barrels so there can be 6 barrels rolling down at a time.

Q: Do the barrels roll all the way down to the bottom? Do they fall out of the set, and need to be reinserted into the slot, or does the mechanism bring them back to the top?

The barrels roll all the way from the top to the bottom where they are collected in a hopper that is connected to the barrel pump. This forms an infinite barrel loop which is, by definition, “barrels of fun”.

Q: What was the biggest hurdle in designing and testing that mechanism?

The biggest challenge was getting the barrels to roll down slowly without stopping or getting stuck. This was achieved through a combination of rolling over steps, LEGO studs, slopes, bows and using LEGO Technic beams which are slightly thinner than LEGO Bricks. This allowed us to capture the feeling of the gameplay where the barrel rolls down slowly. I rolled thousands of barrels down those tracks to figure it out… Those barrels drove me bananas!

The second biggest hurdle was finding a way to get the barrel from the bottom to the top again. We built all kinds of stuff; things to shoot one barrel from the bottom to the top, worm gears, force multiplication levers, and more. But it turned the right answer was simply a lot more barrels.

Q: How do the joystick and button make Jumpman/Mario move?

The joystick moves Jumpman from left to right using a long lever up the back of the model, connected to a dingler. The jump button uses a similar mechanism used in a piano key. When it is pressed down in front of the model, the other end of a see-saw lever presses up on a long rod with Jumpman at the top. When the button is released gravity returns Jumpman to the bottom.