Update: It looks like some signals got crossed. This is the Sony Xperia Z1 Compact - the "Z1s" is a T-Mobile branded variant of the original 5-inch phone.
It's been said that those who want a powerful modern smartphone with a non-gigantic screen don't have a lot of options. If a new post from the tireless Evleaks is to be believed, they'll have at least one more on T-Mobile very soon.
When Matt reviewed Tiny Bang Story yesterday, he found it big on imagination, but gameplay came up short. If the $3 price tag was too large of a risk for you, though, maybe this sale will be more your size. HeroCraft has shrunk the price by two thirds, bringing it down to an outright miniscule $1. Any smaller and you'd need a magnifying glass to find it.
One of the great things about Android's ecosystem is the number of indie developers who are able to enter the market successfully, providing a great product and inspiring would-be developers to join in. For many though, Android development in general is a mysterious topic. How an app or game goes from an idea to an entry in the Play Store is unknown, but (thankfully) not unknowable.
Of course, considering how major development studios bring apps to life doesn't require too much thought – major companies like EA, Disney, or Rockstar have no problem hiring designers and developers to crank out and maintain polished apps.