Within six days it had achieved the same accolade in the US on both iPhone and iPad, where it stayed at the top of the charts for a full two weeks all without being featured by Apple.
By the end of 2012 over 200 million games of Plague Inc. had been played and the game was the 15th most popular paid iPhone game and one of the top 100 grossing apps of 2012 in the US no mean feat for the first game from a first time game developer.
25-year-old Londoner James Vaughan was working as a strategy consultant when he decided to create his first iOS game.
"I had never worked in the games industry but when I was younger, I used to make maps and scenarios for a wonderful game called Age of Wonders Shadow Magic," he says.
"I think this taught me some useful lessons, which helped me make Plague Inc."
First steps
By 2011, when Vaughan was working on the game as a hobby, stories of independently created games that struck gold on the App Store had all but dried up.
A weighty marketing spend and a warm relationship with Apple appeared to be essentials for establishing a hit on the platform.
Age of Wonders Shadow Magic
"I had read all over the internet how hard it was to succeed on the App Store so I didn't want to get my hopes up," he says.
"My success criteria was very simple make and release a game of which I was proud. My stretch goal was to not make a loss on the game i.e. make back my development costs, which were sub-$5,000."
Vaughan, a fan of strategy games, looked at the App Store to see what kind of title he would make.
"A key inspiration for Plague Inc. came from a 2008 Flash game called Pandemic 2 and I have always been very open about this," he says.
"I thought that it was a great game but that it could be so much better so, I decided to make the game that I wanted to play."
Pandemic 2.5 is a game that turns video games' traditional 'save the world' premise on its head, granting you a new bacterial disease, asking you to name it before making you responsible for its development and growth.
Your goal is simple, dark and delicious: infect the world and exterminate all human life as quickly as you can.
Playing Pandemic
But this source material has also been a source of some contention since Plague Inc.'s subsequent success.
While Vaughan introduced a number of new features to the Pandemic 2.5 template, some view his work as being something of a clone.
"The first thing I did when writing my design document for Plague Inc. was to clearly outline how Plague Inc. would innovate and expand the genre created by Pandemic," says Vaughan.
"There is no honour in mindlessly copying someone else's game I wanted to make absolutely sure that Plague Inc. could innovate enough to be a unique game, standing strongly on its own to be something I could be proud of."
Pandemic 2.5 on iOS
Vaughan embellished Pandemic's template by adding more story, offering the player more strategic choices, providing graphs/data lists and increasing the realism of the world.
"Since the release of the game, I have kept expanding the game by adding in new gameplay mechanics e.g. the Necroa Virus update adds a zombie plague with'active abilities' a way for the player to impact specific countries," he says.
Vaughan created the algorithms for the game in Excel before working with a small team of freelancers to realise his idea.
"A programmer created the game engine to hold my algorithms; a graphics designer turned my horrible wireframes into beautiful art and a sound designer gave me the music and sound effects I needed - his daughter sings the Ring a Roses song inside the game. We are all still working together on updates for Plague Inc."
Viral spread
The designer was on holiday in Ireland with his girlfriend when he heard that the game had passed Apple's certification process and been made available on the store.
"I woke up one morning, saw that it had released and instantly jumped out of bed to email all my friends about it and read player reviews," he says.
Success was instant but, when it comes to establishing why, Vaughan can only make educated guesses.
"I can't say for sure but I think Plague Inc. rose up the charts for one key reason: it sits firmly in an underdeveloped niche - intelligent, realistic and sophisticated strategy games - and so is unlike any other game on the App Store. This helps it grow organically and spread virally."
By the end of last year Vaughan was able to leave his job and work full time on the game. In October, Plague Inc. launched onto Google Play and the Amazon App Store and is also now available in German, Spanish, Brazilian Portuguese, Italian and French.
This year, Ndemic Creations will continue work on Plague Inc., follow up games and brand new games ands Vaughan hopes to expand the team with some new hires soon.
It's fitting, perhaps, that a game about the spread of a virus should go viral so quickly, transforming the lives of those involved. For Vaughan, Plague Inc. has been a positive disruption.
"I really am having the time of my life," he says.
You can read the full interview with James Vaughan here.
