A great game....for a bit. It starts off really well, then it becomes to next to impossible without better weaponry. The rate at which you are awarded weapons and upgrades decreases rapidly, just in time for the harder levels. Luckily, there's a way you can get the upgrades you need....spend real money. Why can't developers just make a decent, honest game? I don't want to give you £85 for some 'gems'.