Ironhide Game Studio is finally working on a Android version of Kingdom Rush Frontiers. The developer posted a video previewing the beta version for Android a few days ago, but no official release date has been set.
The second game of the popular Tower Defense franchise was released for iOS devices on June 6, 2013. Ironhide eventually released an expansion entitled "Rising Tide" a few weeks later, but gave no mention of an Android, Steam or Flash release, which did not sit well with Android fans. However, the developer has heard the many, many complaints, and has begun working on an Android version.
Kingdom Rush Frontiers is considered one of the best Tower Defense games ever released for iOS devices. The original game was released as a free Flash version, and was eventually ported to iOS and Android devices after its popularity grew. Both games are medieval defense games where users must ward off advancing enemy armies with their towers, soldiers and magic spells.