'Accidents happen', as the saying goes, and although we'd like to think of our favourite gaming studios as messianic conjurers of code who just pulled grade-A ideas out their collective rumps one after the other - sometimes such things just land in their laps instead.
Let's take a step back though - what makes good game design? Is it Call of Duty or Battlefield's hands-off approach that guides you through a number of set-pieces all with essentially everyone experiencing the same thing? How about Metal Gear Solid V, GTA V or Red Dead Redemption, who give you a handful of narrative setups, but ask you to figure out how to complete them?
There's even the Uncharted series who'll design an extended physics-based level (like a train thundering down the track, or a collapsing building) whilst retaining your control to navigate the whole thing in real time.
Each one of these is a work of genius, but when it comes to analysing the train of thought that put them together in the first place, that's where the games industry is woefully lacking in showing off. Only recently did Sony put together their 'Conversations with Creators' series where we got insight into the creative process behind your favourite titles, so it's only when you start digging through gaming's history you realise just how many landmark, iconic and defining elements actually came together by chance, accident, or a combination of the two.