The video game clone has been around since the dawn of the medium, as developers attempted to build on the ideas of others... or maybe they were just ripping them off. It's a sticky situation. Most developers understandably don't want to discuss it, but the subject keeps coming up. This is thanks in no small part part to the popularity of platforms like the iPhone, Facebook, and other digital delivery outlets where being first to the market is often a primary factor in success. The result is a proliferation of games that both look and play very similarly, if not identically, and plenty of titles that have been forced to change or else be taken off the market. But what exactly defines a clone? Is there a fine line that separates theft from inspiration? Ars investigates, and thatgamecompany's Jenova Chen provides his own take on the issue.

"I think the fine line between a clone and a product influenced by others is very similar to our college essay standard," Jenova Chen, cofounder and creative director of thatgamecompany told Ars. Chen is the main visionary behind games like Flower and flOw. "You can reference some one's work by quoting and giving credit to them or digesting their material and summarizing it in your own words. It won't count as plagiarism as long as you don't directly copy and paste other people's work without adding your own."

Of course, it's not always that simple. "Miss one element, whether it's the visual or the story, [and] the whole gameplay will be very different," he said. "A platforming game without Mario won't have the Mario experience."

Chen became tangled up in the messy world of game clones when he spotted a free iPhone game called Aquatica, which looked nearly identical to TGC's flOw and initially did not reference the original creator.

"The whole event regarding to Aquatica is unfortunate," Chen explained. "The developer really loved flOw and wanted to create something just like that on iPhone. It could be a wonderful thing for both parties if presented properly. He recreated the entire game by himself thinking it wouldn't be plagiarism. However, just like a college essay, if you write down all the sentences yourself but the use of the words within these sentences are from other people's work, we consider it plagiarism. It just doesn't feel right, when there is almost nothing significant changed in Aquatica compared to flOw. Even a different background color could have made the difference.

"What bothers me the most is that because of my own overreaction, I might have created a lot of inconvenience to the creator of Aquatica and interrupted his game making," he added. "He is clearly talented, and certainly a fan of flOw. I hope he can continue creating video games, but with his own design."

The developer has since made the game unavailable, saying on its website: "Because the game seemed to be upsetting so many, we have decided to remove it completely. We will also make sure nothing like this ever happens in the future—we understand our mistake, and will be working very hard to correct it and make amends."

Tthe iPhone has become notorious for this sort of thing. Games like Peggie—a game that not only has a similar title to PopCap's addictive puzzle game Peggle, but plays similarly, as well—have been forced to change or run the risk of being pulled from the app store. Meanwhile, The Tetris Company seems to be constantly rooting out games that could be confused with the legendary falling block puzzle game. We contacted both PopCap and The Tetris Company to discuss the matter, but both declined to comment.

What's interesting about these two examples is the double-standard that seems to be in place. Peggie wasn't forced to change the way it plays in any way—despite the similarities to Peggle—just its name. The same goes for a game like Bejeweled, which popularized the match-three puzzle formula, which can now be seen in numerous other games including the Puzzle Quest series. These forms of gameplay appear to be fair game, yet the Tetris formula is not. Lining up rows of blocks is just a game mechanic, but those now-iconic shapes? Off the market.

Things are just as bad on one of the fastest growing gaming platforms, Facebook. The social network features numerous, near-identical games in different genres, like farming or restaurant management. Being the first developer to release a new type of the game on the service is very important to garner an audience, so companies race to get titles out as fast as possible. Just look at these two images from Zynga's Cafe World and Playfish's Restaurant City, the two most popular restaurant sims on Facebook.

Cafe World by Zynga.

Restaurant City by Playfish.

Everything from the menus to the graphics to the on-screen display is nearly identical, this despite the fact that Cafe World was released nearly six months after Restaurant City. Playfish, which was recently purchased by Electronic Arts, is one of the few developers on the platform that doesn't seem to take this approach, instead focusing on quality games that actually bring something new to the table. The company's farming title Country Story, for example, is an objective-based game that differs greatly from competing games like FarmVille, Farm Town, and Island Paradise.

"We do have a hands-off stance on the subject since it just wouldn't be appropriate for Playfish to comment on competitors' games," Playfish director of global communications Tom Sarris told Ars. "It really all simply boils down to a philosophical difference in the approach to development, and we don't feel there's necessarily a right or wrong way at this point. The marketplace will ultimately be the judge."

And the marketplace has judged. According to AllFacebook.com, while Playfish and Zynga are the top two developers on the platform, Zynga has nearly four times the market share of Playfish, with approximately 214 million monthly active users across all of its games, showing that consumers aren't necessarily all that concerned with originality. But, of course, just because developers can do something, doesn't mean they should.

"I don't like plagiarism, because it's a product of laziness," Chen told Ars. "It does no good but waste the time of people who have seen similar things before. However, 'standing on the giant's shoulder' is about creating something new on top of what's good from the past. And that kind of reference and inspiration are always welcomed."