It could be easy for a mobile app such as Plants Vs Zombies 2 to get lost among the gaming big guns at this year's E3 - the world's largest gaming trade show - but that's not the case.Behind closed doors at EA's mobile platform presentation - the publisher that snapped up Popcap, the developer of the original app - we sat eagerly on a cushy white couch, iPad in hand, near-butterflies in stomach in anticipation of playing. Why? Because the original Plants Vs Zombies is that good.Affectionately introduced to us as "PVZ2", the title maintains the good stuff of the original: it's got the same core mechanics and is accessible from the getgo.The game's premise is that Crazy Dave - some bloke with a saucepan on his head who makes absurd noises - has invented a time machine. But things have gone wrong in its use and we're transported to ancient Egypt where there are zombies out to eat your brains. Why? Because that's what zombies do, we s'pose. But it gets stranger: plants can be deployed, each with their individual superpower, to shoot at or protect you from the zombies' advance.The angled view on to the single-screen gaming landscape shows five rows that zombies can proceed down. Each is divided into nine sections where plants can be placed. It's the same basic mechanic as the original game, but it works because it's simple and manageable. We did wonder if larger levels would appear, but that's not the case.Instead PVZ2 has gone a bit "Mario". The game path is still linear, but in the same way that Mario Wii U has maps with individual levels, so too does PVZ2. Start at the beginning, progress and save as you go. On the map gates can be unlocked to access permanent power-ups and acquire new plants in different worlds.Egypt is one world, comprised of 26 levels, but there are two other themed worlds at launch: the Wild West and pirates. There's also a blacked-out third world that looks like alien spaceships to us, and more worlds will unlock free of charge in the future.Within each level there are new tweaks. The core plant-to-defend mechanic remains, but in the Wild West, for example, there are minecart tracks where plants can be deployed in the carts and repositioned in real time to add to your defence. It gives the game a feel that's less rigid. There are themed zombies too: trios pretending to be camels in Egypt, rope-swinging pirates in the scurvy seas and others of which\u00a0we're yet to get full details. The elusive Yeti makes a reappearance too.There are also new power-ups included in play. Plant food can be dropped on to any rooted plant to give it a brief superpower - the Peashooter shoots at 10-times the speed for a few seconds, obliterating everything in its path, for example, while other plants receive similarly explosive superpowers. Plant food can be collected from glowing green zombies or purchased using in-game coins.Additional power-up controls based at the bottom of the screen also change the mode of play slightly: pinch to pop heads, swipe to push zombies into the next row or swipe for a gust of wind that\u00a0pushes zombies off screen. Each costs in-game coins ranging from 800-1,000 per use, but can help get you out of a sticky spot when a huge wave of zombies comes in on the attack.There are also premium always-on power-ups which can be purchased alongside six premium plants - these range from extra sun when digging up plants, to more sun at the start of a level, and so forth. But only the plant-food-producing Power Lily is new; the other premium plants are classics such as Squash, Torchwood, Snow Pea and Jalapeno. How much these will be to buy in real money terms is yet to be determined - all that was confirmed is that it will cost for each plant rather than all as a group and that once purchased the option to continue to use said plant would remain in the game's arsenal thereafter.We played through a few levels in each available world and found it a lot of fun. There are new standard plants available - Boomerang, Pea Pod, Coconut Cannon, fire-breathing Snap Dragon, and Bonk Choy thrown in among other favourites - to keep the gaming fresh despite the familiar experience.If Plants Vs Zombies 2 is a couple of quid to buy when it's released on iOS in July (possibly August, Apple dependent) then it's got to be a game to snap up. An Android version is also in production, but won't be released until a few months after the iOS version, while other platforms aren't yet confirmed in concrete, but there's talk of a 2014 potential release for what we can only presume will be a Windows Phone 8 version.Now go make some Crazy Dave noises in anticipation for this one. It already looks to have its sights set on app of the year, not just app of the day. Top stuff.