When we heard that Not Doppler, the makers of zombie smash-a-thon Earn To Die, was releasing its latest iPhone title, Bunny Cannon, we anticipated more fast-paced blood, guts 'n' gore. But no. Bunny Cannon merges cute and cuddly kid-friendly graphics over a seriously challenging set of levels. It's tricky, sometimes seemingly impossible gaming, but it'll keep you coming back for more... just like a rabbit on heat.Bunny Cannon\nFormat\niPhone | iPad\nPrice\n\u00a30.69 | \u00a31.49\nWhere\niTunes | (iPad HD version)\nThe ultimate goal of Bunny Cannon is to pop at least the minimum number of earmarked - see what we did there - bunnies into corresponding boy\/girl\/mixed baskets to pass to the next level. There's some storyline about "where bunnies come from" but, frankly, you'll be too busy desperately willing that last bunny to ping into an obscurely placed basket that you won't have much care much for storyline.But that's a good thing. While Bunny Cannon starts up simple, and without much of an education in how it all works, a couple of easy levels will pass by in which you'll have to use your intuition to work it all out. Then it's all about honing your timing and, well, patience to continue through the more advanced levels. There are 90 levels available in the initial download with more anticipated in future updates.The game mechanics are simple: there are a set number of boy and girl bunnies - represented by blue and pink, stereotype fans - that you can fire from the cannon at the top of the screen. Strike opposite bunnies and they multiply with, you guessed it, yet more bunnies.That's the short of it, but it's not nearly as easy as it sounds. Each level provides a set number of bunnies, in a specific order, which can make it tricky to strike the desired opposite sex. The cannon can be moved across its rail to the top of the screen, though sometimes this is strategically blocked in certain levels, while the force at which you launch your poor rabbit friends out is adjustable by pressing the device's screen and pulling away at a given distance for increased strength.Add killer owls, moving objects, one-hit destructable blocks, pitfalls, deadly thorns, Indiana-Jones-style rolling rocks and it promptly gets tough. So much so that some levels seem like a stroke of luck to pass through, which in many ways is the biggest frustration with this game - it's a smattering of luck as well as honed skill.It's difficult to not compare a lot of games to Angry Birds these days, or at least the now well-established "three star" scoring system, and Bunny Cannon opts in for a similar reward system. Get the minimum number of bunnies in baskets for a single star, some extras will award two out of three, and far tougher scores - at least for most levels - will result in the full three out of three. It will keep you going back. It's a pride thing - who wants to be outsmarted by a bloomin' owl? Nobody, that's (twit-t) who.Fancy a challenge, then go grab Bunny Cannon. It's 69 pence of pocket change (or \u00a31.49 for the iPad HD version) that will see you ride the emotion 'coaster from charmed to downright peeved off, but in that classic gaming way that'll keep you coming back, hungry for more.