Pigs VS Wolves (2010), featured on the iPho Game Development Website, is Digiarty Software's recently released tower defense game, available on iTunes, for the iPod Touch/iPhone. Pigs VS Wolves comes out hot on the heels of powerhouse PopCap Games strikingly similar, but higher profile, Plants vs Zombies, which, besides being available on the iPod Touch/iPhone, also has versions available for the PC, Mac, and Web. Not having played Plants vs Zombies, besides the obvious visual differences, the only other major distinction that I can see is the price. Plants vs Zombies runs $2.99, while Pigs VS Wolves is just $.99--at least for a limited time. Therefore, without a true basis for comparison, I will only review Pigs VS Wolves on its own merits, keeping in mind the existence of the prior product from a much larger developer/publisher.
Tower defense games are considered a sub-genre of real-time strategy games, with the most basic goal to stop enemies from reaching a particular point. Wikipedia points to Atari's Rampart, a 1990 arcade game from Atari, as forming the foundation of this sub-genre's roots. While I think that simplifies history a bit and minimizes the truly hybrid nature of Rampart - which I argue is part Tetris - it's ultimately a fair assertion. One of my personal favorites in this sub-genre is PixelJunk Monsters (Q-Games, 2008; Sony PlayStation 3 (PSN)), though I've certainly played my share of others, including South Park Let's Go Tower Defense Play! (Doublesix, 2009; Microsoft Xbox 360 (Xbox Live Arcade)), that I've tended to like much less. Major distinctions between the tower defense games include how much real-time elements there are and of course the overall imagination and cohesiveness that goes into all of the defensive and board designs. The vast majority of these games feature levels that start out simple but progressively add more playing pieces to the mix, requiring an increasing amount of thought in both defensive selection and asset allocation, as well as an increasing amount of trial and error to both learn new capabilities and properly utilize them to fight off the hoards of enemies.
The developer describes Pigs VS Wolves as follows (and we must at least partially forgive their non-native English):