Castlestorm: Free to Siege is a smorgasbord of gameplay styles. At its core it is a tower defence game, but it ladels in construction, brawling, and even physics destruction elements in its gameplay stew.

You begin each stage facing off against your medieval enemy along a 2D path. Sometimes your goal will be to stop all of the advancing attackers. At other times you'll need bring down the enemy's fortifications using any or all of the plentiful combat systems at your disposal.

The first method of attack on offer is the ballista. Tapping anywhere on screen will unleash a volly of javelins or other projectiles. This lobbing mechanic proves especially useful when bombarding your foe's fort. Heavier projectiles possess special abilities that cause them to speed up, explode, and even split into three a la Angry Birds. The physics are less weighty than the avian blockbuster it imitates, but prove no less enjoyable.

If projectiles aren’t enough, then you can also call in the troops using two seperate systems. The first follows the standard tower defence formula, with you spawning swordsmen, archers, priests, and numerous other unit types to defend your castle at the touch of a button.

The other, more satisfying option is to summon a hero. Once spawned, you lead your warrior into battle using the responsive virtual stick and buttons. Operating under your direct command, this powerful unit temporarily turns the game into a side-scrolling brawler. When used wisely, the hero becomes one of the most entertaining parts of the game, and often the lynchpin to victory.

Castlestorm doesn’t stop at physics-flinging and arcade combat, though. As well as reducing opposing castles to rubble, you also get to build your own. Different rooms and defences can be cobbled together to create a sturdy base capable of providing gamplay buffs. A simple grid-based design allows you to easily snap rooms into place but, despite the ease of the system, it feels overly complicated for the slight advantages it offers.

What's impressive is that all of the disperate of Castlestorm: Free to Siege come together brilliantly. While it does aggressively advertise its in-app purchases, this is an ambitious and involving free to play release which offers tonnes of entertaining strategy and action gameplay with very few restrictions.