Flash tower defence game GemCraft now zaps the hordes on iPhone

There are plenty of tower defence games, but not so many can boost 90 million plays when it comes to their Flash version.

And that's the background to Japanese publisher NTT Resonant's decision to release Game In A Bottle's GemCraft for iPhone and iPod touch.

The Hungarian studio originally launched the game in 2008, and since then has released a further two versions.

Mixing up RPG elements with basic tower defence elements, GemCraft has you actually building towers in which you then set gems in order to destroy columns of nasties out to destroy unsuspecting villages.

The point of the game is to create and combine gems to vary their power in terms of level and attributes such as range, damage and firing speed, and magical powers such as multiple targeting and poisoning. You can also throw gems to cause area damage and slow the enemy by laying down water barriers. You can add gems to these.

The key resource you have to use carefully is mana, which is required for each tower and gem created, and for combining gems too.

The iPhone version of the game is spread across four worlds and 32 levels, each of which have seven gameplay modes to unlock. For release on the App Store, the game's been updated with optimised graphics, a new user interface, new levels, online leaderboards and achievements.

GemCraft is out now for iPhone and iPod touch, and for a limited time, priced at $1.99, €1.59 or £1.19.

There's also a free version available [iTunes link]