Released by a small Swedish studio for iPhone in early 2012, competitive word game Ruzzlehas now been downloaded over 45 million times.
This performance is a mark of developer MAG Interactive's constant attention, not to mention its ability to keep rolling out support for new languages.
The game is now available in 13 languages, with Russian, Turkish and Greek being the most recent.
Additional platform support has also been a focus. As well as iPhone, Ruzzle is now available on Android, Amazon Kindle, Windows Phone, and BlackBerry.
Share and share alike
But according to MAG's CEO Daniel Hasselberg, the main driver of Ruzzle's success has been the ease with which players can share their love for the game.
"We make it easy for players to find their friends and share using Facebook Connect or Twitter," he says.
"We're a small company and don't have much money to spend, but in the US, we've driven 20 million downloads mainly through viral marketing."
Downloads of Ruzzle got a lift in Turkey when language support was added - via App Annie
Another aspect the developer has spent some time on is the game's matchmaking system.
"People usually start playing with their friends, but Ruzzle is a skill game so after a while they'll migrate to playing against random people with same skill level," Hasselberg explains.
At present, the system handles over 4 million random players on a daily basis, with the lifetime cumulative total over 12 billion rounds.
Perhaps the only downside for MAG Interactive is that the single IAP monetisation option for the free game is getting players to spend $2.99 (once) to upgrade to the ad-free premium version, which also has more features in terms of statistics.
This means its chart performance tends to follow the trajectory of a paid game - high at launch and then a long decline.
Ruzzle's performance on the US iPhone top grossing charts - via App Annie
Despite this Ruzzle has been a top 5 top grossing app in 33 countries, peaking at #8 on the US top grossing charts for iPhone.
As well as IAP, the company generates revenue through the billions of ad impressions it generates per month, something that doesn't show up on the top grossing charts.
It's also using incentivised video ads to enable users to gain temporary access to game stats - access which can then be used to encourage them to buy the premium version of the game.
Italy has been one of the strongest markets for Ruzzle - partly because of an advertising campaign run with InMobi.
The UK is the next target for MAG Interactive, with a recent rise up the top grossing charts for iPhone (albeit from a very low base) looking like its marketing has been working well - via App Annie