In the very near future a hitherto unknown type of metal, Sinclairium-256, is discovered in a disused Venezuelan chocolate mine. This new element proves to be extremely strong, light and cheap to produce, and before long train operating companies are queuing up to build their new trains with the miracle metal. Unfortunately, it soon becomes apparent that Sinclairium-256 is dangerously unstable, and if left undisturbed for any length of time has a tendency to explode. In an effort to cut their losses train companies auction off their new rolling stock to the highest bidder, and this turns out to be an online bingo company.

Chug Horncastle is an experimental self-aware Sinclairium-256 driverless locomotive, and his new owners put him to use on their satellite television channel. The trucks have all been painted with numbers from 1-90, and Chug has to shunt them around the yards and sheds until they fall through holes in the floor. The corresponding numbers on the side of these trucks are then called in a giant interactive bingo game. With substantial prizes on offer, Chug cannot resist having a flutter on the game himself, especially as he will be selecting the numbers.

Chug moves left and right and leaps from one platform to another.

Trucks drop from the top of the screen, and Chug may manipulate them around by pushing them. When a truck falls off the bottom of the screen its number is called in the bingo game. If this number appears on Chug's card, shown at the top-right of the screen, the number flips over and once all numbers on Chug's card have flipped he may progress to the next stage. However, if the number does not appear on Chug's card ten seconds are deducted from his time limit. When five minutes have elapsed, Chug loses one of his three lives.

Pushing two trucks together will combine them into a single truck with a different number, usually the combined total of the two. If the numbers added together come to more than ninety, then the smallest number will be subtracted from the largest to form the new number. However, if these two numbers are identical the new number will be a third random number. The following table gives an illustration of the numbers one might expect:

I hope your mental arithmetic is up to the job!

On later levels, local moral campaigner Edna Bucket makes an appearance. Having succeeded in her attempt to ban naked ankles from appearing on network television Edna turns her attention to satellite gambling channels, and embarks on a terrorist onslaught blowing up the trucks with her patented Nitro-Glycerine handbag. Chug's life is never simple.