Game devs looking to enhance "engagement" (read: monetization) for their mobile titles now have an ally in Amazon. The Bezos-backed company has just made plug-ins available free to Kindle Fire developers using the popular Unity game engine. Now those devs will have access to APIs for In-Game purchasing and GameCircle which, in the latter case, allows for the addition of Achievements, as well as the ability to Whispersync across devices. So, what does this mean for you, the end user? Well, aside from the ability to continue playing from where you last left off on any of the company's tabs, it also brings mobile gaming that much closer to the console experience. But mostly that you can look forward to a future bill filled with micropayments.