Flood the moat! Bar the gates! The castle's under siege! CastleStorm: Free to Siege brings medieval castle defense mayhem to the iOS. Going free-to-play often spells irritation for gamers, but CastleStorm's unique take on this marketing approach may leave you with some extra money in your pocket and a song of annihilation in your heart.

In CastleStorm: Free to Siege, you'll spend most of your time defending your castle while trying to crush your foe's fortress. A constant stream of enemies moves in on your keep, and to counter them you can use magic, with spells like lightning bolts, summoned heroes (who you can control like side-scrolling beat 'em up characters), and blazing meteors all raining destruction with satisfying flair. You won't have to worry about managing magic points, however, as each individual spell has its own cooldown, so use them as you see fit.

Zen Studios

As you slay enemies you'll gather food to raise an army of your own, like cheap, but weak footmen, ranged archers, strong, but slow paladins... there are options a-plenty when deciding what kind of army to form. Most of your power comes in the form of your ballista and its many different ammunitions. Standard ballista harpoons fire quickly and precisely, dealing great damage with headshots, but lacking enough weight to cause much true destruction. You can also lob explosive boulders, magical allegiance potions to convert strong foes to your side, deadly eagles, fart-propelled rainbow sheep... the list goes on and on. Each ballista shot has a nice heft and effect to it, letting you really feel the devastation as you crumble your opponent's castle.

Zen Studios

With each successful level you complete, you'll earn money to upgrade and customize your castle and armaments. There are far more types of ballista shots, magic spells and military units available than what you're allowed to bring with you to battle, so in between each skirmish you'll have to make some tough decisions about which armaments to use and upgrade. Your castle's layout can also be customized extensively. You can add a variety of different rooms to the keep to confer different bonuses, and alter the layout to make it more resistant to damage.

Zen Studios

CastleStorm offers several fairly lengthy campaigns, each with their own fun storylines to follow, different characters, abilities, and weapons to master, and variant levels that mix up the typical protect your fortress/smash theirs experience. The story's not exactly complex, but it's straightforward and worth a few laughs, which makes it leaps-and-bounds better than the stories you'll find in other, similar titles.

The transition from PC to iOS meant that CastleStorm was going to have to make some major changes, control-wise. The PC iteration of CastleStorm rewards players for precise attacks using the mouse— a much more difficult task on a touch screen. Still, the controls do their job, and while you may occasionally lose your kill streak/headshot bonus because of a misread tap of the screen, it's never enough to cause any substantial frustration.

Zen Studios

As you might expect with a free-to-play title, CastleStorm offers plenty of gems and gold coins that you can exchange your real coins for, and an endless number of ads to endure, but with a game-changing catch. Make a purchase of any level from the in-app store and the ads will disappear forever; purchase the five-dollar VIP package (which is a generous price for a game with this much content) and the ads don't just disappear, but CastleStorm also gives you a weekly allowance of gold coins and all-powerful gems, giving you full access to every bit of content so long as you have the patience for it. It's a welcome change to the greedy formula seen so often in free-to-play games, and something that more game developers should learn from.

With combat that's fast-paced, yet thoughtful, extensive customization and upgrade options, lengthy campaigns, and a generous approach to free-to-play, CastleStorm: Free to Siege has turned out to be one heck of a title, one well worth the time of anyone in the mood for some finger-blazingly frenetic action.

This review is based on a download code for CastleStorm: Free to Siege provided by the publisher for iOS.

App Store Link: CastleStorm: Free to Siege for iPhone and iPad | By ZEN Studios I Price: Free | Version: 1.0.1 | 367 MB| Rating 12+

8.5 out of 10 arcade sushi rating