Some see Flappy Bird's rise as the ultimate viral success story; an incredibly simple game that rose to become a global sensation through word of mouth, self-sustaining buzz, and a punishing difficulty ("Hey, I bet you can't even score TWO on this game!" "Oh YEAH?!"). But through the game's brief popularity (and subsequent takedown by its creator), there's been a subtext suggesting that Flappy Bird's success was less than organic, driven by sham downloads and/or reviews that drove the game up the app store charts. That subtext has risen to the level of self-evident text for many observers, who simply can't believe that such a simple game got so popular so quickly on its own merits.

The truth of the matter is tough to pin down, but it did get us wondering: how easy is it to game the App Store rating system? (This story focuses on the iOS App Store, but it's applicable to other online stores as well.) Can you really buy your way to a No. 1 app store ranking and reported revenues of $50,000 a day by using networks of bots or paid shills? If so, is there anything being done to try to stop it?

Freaking rankings, how do they work?

To answer that question, we first have to figure out how Apple generates the all-important rankings you see when you look at the Top Charts tab in the iTunes store. Apple itself keeps its algorithm largely opaque, probably to help prevent just the kind of gaming being discussed here, but that hasn't stopped observant data miners from trying to figure out how things work.

In June, analytics firm Distimo estimated that it takes about 23,000 downloads in a single day to reach the top 50 in the "free" game charts, and about 72,000 to reach the top 10. A September study by app maker Readdle suggests it takes as few as 4,000 downloads to reach the top 10 on the paid app charts. That provides a decent baseline for how many "inorganic" downloads you'd need to generate to work your way up the charts (assuming your chicanery wasn't detected and filtered out).

With so much visibility at stake in prominent Top Chart placement, there's plenty of incentive to get those downloads by any means necessary. There are a number of ways to do this, some more ethically questionable than others. On one end of the spectrum is plain old mobile banner advertising, which is sometimes paid on a "per install" basis. Other services, like ChartBoost, include the ability to essentially trade cross-app promotion with other developers, taking money out of the equation to some extent.

Some services go a little further, asking players to install promoted apps in order to earn in-game rewards, though Apple started cracking down on this practice in 2011. Other app-based services get downright annoying, sending push notifications asking you to download the latest free app they are promoting; Apple took steps to block these last year.

On the extreme scummy end of the spectrum are automated networks that sign up for countless fake iTunes accounts, generating illicit download traffic to push an app up the charts. Inside Mobile Apps noted back in early 2012 that it was a "well-known secret" that many top apps got there with the help of such a bot network. One app marketer reportedly admitted this quite openly:

I was totally SHOCKED when I heard that there were 8 apps on the Top 25 Free App store that were all promoted by [an unnamed marketing service]. At this point, I was pretty curious on how he's able to do that (I was told by an AdMob sales person before that it takes a lot of money and traffic to promote an app to the Top 10). That’s when he let loose the BIGGEST FRAUD ever; he said he had outsourced someone to build him a bot farm, and the bots will automatically download his clients' apps and drive up their rankings!!! He even told me that even though I might see my app climb up the app store, they aren’t "REAL" at first until it gets to the top, and that’s when REAL HUMAN players will start seeing my app and play it.

Other developers reported signing up for what seemed like reputable ad networks, only to suspect bots were involved when they saw "downloads without any corresponding bump in active usage," as Inside Mobile Apps put it. "It was presented as an ad network, but it became obvious to us that users weren't even launching the app. So we stopped using it after that," Micah Adler, CEO of user acquisition company Fiksu said at the time.

Apple is constantly tweaking its ranking algorithm to make the scummiest of these promotional methods ineffective. A major algorithm shift in 2011 and another in 2012 seemed to limit the effects of download bots by taking active usage and other statistics into account. The result is a marginalization of many of the worst methods of artificial ranking inflation used in recent years.

"Last year was all about chart-boosting, buying as many app installs as possible in as short a timeframe as possible to get to the top of the charts," Bill Clifford, chief revenue officer at mobile ad firm SessionM told AdWeek in a December interview. "Now there are fewer loopholes available to artificially inflate rankings, and legit companies won't spend their time with it."

Buying reviews and “organic uplift”

It's not impossible to buy installations these days, of course; there's nothing stopping a company from simply flooding the mobile banner ad market to get a bevy of quick downloads, for instance. But it does seem to be more expensive to purchase app downloads now that Apple is on the lookout for the most egregious methods of fakery. And prices can spike during busy periods.

That doesn't mean it's not still worth it to buy your way to the top, though. A June study by app marketing firm TradeMob noted that, for every installation an app maker pays for directly (meaning the cost to get a person or a bot to install an app, not the cost of the app itself), that app maker can expect a certain number of "free" installs by dint of being listed higher on those heavily trafficked top charts. The firm determined that this "organic uplift" was worth an extra 65 percent value for non-game apps and a 100 percent increase in value for games.

So while it might cost $1.40 to buy a single installation of a game, according to TradeMob, the "effective cost" goes down to 70 cents when you consider the extra "free" download that will be driven by increased chart placement. Total estimated cost to reach the top ten list: $96,000.

Buying installs directly isn't the only way to worm your way to the top of the charts these days, though. Last August, Fiksu noticed what appeared to be another change in Apple's ranking algorithm. Since July, apps with higher average rankings from iTunes reviews were doing much better than those with worse reviews.

You can probably predict what came next: sites like SafeRankPro, BuyAppStoreReviews, BestReviewApp, AppRebates, and more popped up just a Google search away, promising real, high quality reviews and ratings of your app, for a price.

"Massive exposure and good reviews and ratings are essential for app promotion and lead to increased sales and rankings," the marketing spiel on BestReviewApp says. "For a fraction of the cost of conventional advertising, we can give your apps a serious leg up in climbing rankings..." according to AppRebates.

Or why not make a few extra bucks by signing up to write those reviews on the other end (mirroring, in a way, the "bribe to install" trend that started popping up in late 2010). Everyone wins... except people who want to trust the App Store rankings...

What about Flappy Bird?

Which brings us back around to the original question: Did creator Dong Nguyen (or someone else) pay to artificially increase Flappy Bird's popularity, at least at first? (It seems clear from Internet reactions that, at some point, organic interest in the game became real enough to be self-sustaining).

There is plenty of circumstantial evidence that something fishy was going on. Blue Cloud Solutions prominently notes the sudden rise of three of Nguyen's games starting in December, months after their release, despite no actual cross-promotion through the apps themselves (it should be noted that Nguyen's other apps appeared on the iTunes store page for Flappy Bird, though). Others have also noted some suspicious word patterns in the flood of iTunes reviews for the game, or noticed the incredible acceleration of Flappy Bird review posting rates starting in January.

This is all interesting, but none of it quite proves any shenanigans to game the system. Some have suggested that users on Twitter seem to have spontaneously started competing (possibly ironically, at first) to create the best/stupidest review of the game, leading to a viral ranking and attention explosion. Nguyen, for his part, has repeatedly and directly denied that he paid to promote the app in any way and has expressed bafflement at how or why it became so popular so quickly.

The real issue, of course, is the "open secret" that positioning on the App Store can be, and often is, bought, through advertising or other means, despite Apple's continuing efforts to stop the worst ways of gaming the system. As long as that's the case, any game that achieves quick popularity will automatically be suspect in the eyes of a certain portion of the public.