I had some time over the 2011 holidays to tackle a 2009 game I'd sampled but not really dived into -- PopCap's Plants vs. Zombies, a tower-defense game from the publisher responsible for Peggle and Bejeweled, among other casual gaming classics.
The tower defense genre fascinates me because it's fairly recent in origin, yet I can easily imagine simple TD concepts that would have worked on the Atari 2600. The basic idea is that you have towers, of various offensive and defensive types, and the enemy has hordes of various incoming baddies; gameplay requires a balance of planning and improvisation as you set up your towers to deal with the invaders as efficiently and effectively as possible. Wikipedia gives credit to a number of forerunners to the genre going as far back as 1983, but it's really only become established as a genre unto itself within the past five years or so. I really enjoyed Final Fantasy Crystal Chronicles: My Life as a Darklord and Defense Grid: The Awakening, so I was ready to pit a few plants against the walking dead.
Plants vs. Zombies follows a fairly simple model -- the zombies charge across the player's lawn or rooftop via six distinct lanes, and the player installs various plants to take them on. The level layouts never really change -- some have a pool in the center lanes, and the rooftop levels require flowerpots to be built before anything can be planted in some locations -- but there are always six lanes of zombies. The zombies don't move across lanes either, so to some degree the player is guided along a set path -- wherever the first zombie shows up is where your first offensive plant should be placed. The game has an economy, of course -- different plants require different amounts of sunlight, which operates as the game's currency. The player can opt to plant sunflowers early on to increase the amount of resources available, but must also deal with the threats at hand.
A "hardcore" TD game like Defense Grid: The Awakening provides variety by changing up the level designs, forcing the player to deal with more complex enemy paths and new traffic control challenges. It took me a little while to get used to Plants vs. Zombies' simpler model, which provides variety only by introducing new plant and enemy types -- one senses that the game will start to get stale the moment novelty ceases, and the designers had the good sense to end the main story just as that's starting to happen. Even so, some of the plants are almost useless, or are introduced only to be superseded by something similar but much more powerful a few levels later. At least there is some strategy required as the player selects a limited number of seed packets at the beginning of each level, and different plants thrive during daytime and nighttime levels -- but I found myself sticking to a handful of stalwarts after a while, and completely ignored some of the available options. When there are thirty plant varieties available and only 5-8 seed slots, it pays to stick with what works.
Most of the onslaughts are fairly brief, and the game isn't particularly difficult -- I managed to get through the main adventure mode in about 8 hours, and only a few situations required retries, usually because some novel variety of zombie showed up at the last minute when I wasn't prepared for it. There are some levels that function differently -- instead of planting what we can as sunlight permits, a scripted series of plants become available over time and we must make the best use of them we can. This is also true of the game's final boss battle, where it doesn't quite work -- we never feel like we're really defeating the boss, we just have to survive long enough to win.
Fortunately, once that somewhat disappointing climax is past, Plants vs. Zombies has a kick-ass closing theme by Laura Shigihara, complete with an animated music video that's funnier than anything in the game proper. And thanks to the designers who had the foresight to include a REPLAY button afterward -- I replayed it a few times, and have been happy to have this bouncy little J-Pop song stuck in my head. I'd link to the official music video on Youtube, but you should really play the game through and enjoy this cool little reward the way it's meant to be.
Instead, I'll link to Ms. Shigihara's YouTube page, where you can see and listen to some of her other work and covers.
Sometimes playing through a decent if not spectacular game has surprising and unexpected rewards.