Archer Defence v1.6 is the latest version of the game, and introduces Google Play Achievements! There are five achievements available to unlock, and I plan to add more that will come with future releases. Version 1.5 of Archer Defence was released into beta, where the achievement functionality was tested.  Unfortunately, one or two bugs were present in v1.5, these have been fixed in v1.6 and the achievement system was tested in beta. As soon as it was verified that the achievements worked, v1.6 was pushed to production.