Earlier this week, indie developer Nimblebit sparked a round of Internet drama with a tongue-in-cheek thank-you note directed to Zynga. Stripping away the faux gratitude, the three-person Nimblebit team was accusing Zynga of producing a brazen knockoff of its hit iOS game Tiny Tower. Both Tiny Tower and Zynga's Dream Heights let players build and manage their own high-rise apartment building, as well as oversee the lives of its occupants.

While accusations of game design thievery have run rampant on mobile and social platforms in recent years, this is by no means a new phenomenon. Gaming has a long-standing tradition of plagiarism that has been equal parts shameful and crucial to the medium's development. There is a fine line between imitation and iteration, and popular games have always spawned projects that straddle that line. Here are a handful of examples pulled from throughout the last 30 years to help drive that point home. Some were found guilty of cloning in court; others were merely convicted in the court of public opinion. Let us know in the comments if you think these cases crossed the line, and which acts of gaming thievery we might have overlooked!