I just learned something fun this weekend. The seminal videogame Pong from 1972 looked like this:

But there was a problem. Here’s Al Alcorn, the designer/​engineer of the machine:

The paddles on the original Pong didn’t go all the way to the top. There was a defect in the [circuit] – I used a very simple circuit, I had to, to make the paddles, but they didn’t go to the top.

This meant that there could be situation where the ball sneaks up past the paddle at the very top of the screen, and the player cannot do anything to stop it.

You can see it in this video:

But Alcorn decided not to change that:

I could have fixed it, but it turned out to be important, because if you get two good players they could just volley and play the game forever. And the game has to end in about three or four minutes otherwise it’s a failure as a game. So that gap at the top, again – a feature. So that was sort of a happy accident.

“Happy” primarily in the context of the industry – the goal of an arcade game was, after all, to bring in quarters, and this here was the unexpected equivalent of the zero in a casino roulette game. But I wonder if some of this bugginess/​randomness also helped the game feel challenging and surprising, even for skilled players.