Kotaku readers might be familiar with Defiant Development, the Australian studio working on Warco, the first person "shooter" where a video camera is your only weapon. Before Warco, Defiant pushed out a casual mobile title called Rocket Bunnies, which saw moderate success, but I doubt it prepared the studio for the heights its latest game, Ski Safari, has reached in Apple's App Store.
According to intelligence and marketing service App Annie, Ski Safari is the #1 paid app in three countries -- Australia, New Zealand and France -- and in the top five in the United States. Not an easy feat for a legitimate app. How long it stays in the upper rungs of the App Store is anyone's guess, but by simply being in the top 25, it will enjoy significant popularity in the short term.
To this day, getting into (and staying) in the top 25 is undocumented alchemy at best, though Australian studios like Halfbrick and Firemint seem to understand the fundamentals. Who knows, we might shortly be adding Defiant to that list as well.