OTTTD (or 'Over The Top Tower Defence') does a pretty good job of living up to its title. Every stage, you are swarmed by bizarre cartoon aliens, and must erect towers to fight them back. Each vanquished foe leaves behind a bloodied corpse, meaning that, within minutes, your base in drenched in an ocean of gore.

While the action is frantic, the classic tower defence gameplay is easily mastered thanks to its straightforward controls. Tapping on any construction point brings up a radial menu, letting you quickly choose the structure you want to build. Whether you order an explosive rocket launcher, a pulse cannon, or the ever reliable gatling gun, your tower will come crashing to earth within moments of tapping.

Once a tower is in place you can upgrade it, or, for a little more cash, perform complete conversions that change the weapon’s effect. For example, if slowing enemies with a shock turret isn't working, then maybe converting it into a multi-directional Omnicannon capable of attacking multiple enemies will sort out your alien problem.

All of the towers work wonderfully in unison, with different balances of tower type providing decent tactical flex.  As each map only allows a set number of towers, you must make tough decisions about what to build, upgrade, or scrap for cash.

Though the focus of OTTTD may be tower defence, the game also features traditional real-time strategy. You are able to control a team of up to three heroes in battle, allowing you to send them and their abilities where they are needed. There are nine heroes, with our favourite being the no-nonsense assault trooper, christened Bubba Solaris by the random name generator. This heavy takes the fight to the enemy, wading into the middle of battle to instantly plug holes in your defence.

T hough it can be tricky to move the units without accidentally selecting nearby towers, these traditional RTS elements become more compelling as you move through the levels. Before long, towers alone will longer hold the line against the advancing aliens, forcing you to master your troops’ skills.

With its elegant controls OTTTD is a great starting points for beginners, while its RTS elements and upgrade systems keeps the initiated enthralled. Factor in a healthy sense of humour, and you have a tower defence game that will appeal to more than just genre fans.