We're told that imitation is the sincerest form of flattery. Which tells us that flattery is an important part of video game design these days - from subtle hints of influence to blatant plagiarism, game developers love to latch on to a winning formula and run with it as if it was their own. We can't really blame them though, can we? As gamers, the people with money to burn who shell out our cash for the games they put together, we're hard to please. So it makes sense that the developers would be cautious to create a game without a solid, reliable hook to build on. Sure, occasionally we fall in love with some utterly unique, artsy indie gem or daring high-profile surprise which takes risks and can be labelled as truly original, but go have a look at the upcoming Holiday Season release schedule: it's riddled with sequels and safe blockbusters, all building on existing successful ideas. The developers and publishing giants of the industry know their trade by now - pick a genre, pick a popular game that has done well at retail in the past, and "flatter" the hell out of it. As a result we are hammered with contrived third-person cover-based alien-stomper shooters, near-future open-wasteland adventures and gravel-voiced sneaky stealth cliches. It all started somewhere. All of these now overused game designs had their genesis. But often it's not the actual first instance of their existence that proved the most important - Super Mario Bros. wasn't the first platformer, but you can't deny that it became the genre blueprint to be ripped off and shamelessly copied. Sometimes it's a stand-out element of a specific game which changed the future of its genre, sometimes it's a whole new genre altogether. Whatever the case, the ten games we've rounded up for this list have been "borrowed" from more often and more blatantly than any other. Without their legacy to replicate, gaming just wouldn't be the same.