Plants vs. Zombies reminds us why we love PopCap games so much. It takes a well-worn genre—the tower defense game—creates what seems like overly simplistic gameplay, and adds in a dash of cartoony graphics. The trick is that PopCap then continues to twist and shape and pervert the basic gameplay until you're in the middle of something devilishly tricky, second-guessing your earlier decisions. This is pure crack, even if it looks like the cutest game with zombies you've ever seen.

The concept is simple: you are in your house, the zombies are trying to get to you to eat your brains, and your lawn is your last defense. Instead of a twisty path to the goal, your lawn is made up of a grid system of five lanes with nine rows, to start with. The zombies won't move from lane to lane, and you can only put one plant on each square. The power you use to plant your defenses is the light from the sun, and it either falls from the sky or is created by your sunflowers.

Title Plants vs. Zombies Developer PopCap Games Publisher PopCap Games Price $19.99, or $9.99 via Steam Platform PC, Mac

It's a constant game of risk vs. reward. Do I plant more sunflowers—which offer neither defense nor offense but create more sun to create more plants, or do I start strong with plants that shoot peas at the zombies? Do I lay down a walnut to stop the encroaching hoard, or am I too worried about the zombies that can simply pole-vault over them? Is this is a good time to use one of my exploding plants, or would the ensuing crater ruin a slot I could be using for another weapon? Holy hell, is that Michael Jackson dancing the choreography to "Thriller"?

If you think you have the game mastered, things change. You may have to deal with swimming pools, which means you'll have to plan a lilly pad before you can put down anything else. Or, you may be fighting at night, which means you have to create all your own sun-power while relying mostly on fungus-based attacks. And this is just the beginning of the ways the game changes to get you to rethink your strategy; there are also 48 plants you eventually get access to, but you can only bring so many seeds with you into battle. So picking your weapons becomes very important as time goes on, and everyone will find a few favorites to add to their arsenal.

More depth than there first appears

While each level starts off simply, and you quickly learn some strategies, it won't be long until you'll find your play escalating into worrying about getting overwhelmed while trying to collect all the sunlight dropping from the sky, worrying about the defenses you've laid, wondering if you picked the right seeds to bring into battle, and getting freaked out when the game announces that a huge wave of zombies is approaching. It only looks easy at first, and then you realize just how much you're being asked to do as you climb up the ranks.

Every level gives you new seeds, or even new game modes, which means that you're constantly being rewarded by playing. It's nearly impossible to enjoy a play session without unlocking something or seeing something new, which helps to keep you entranced with the game. The PopCap's odd humor is also here in full force, making this is an oddly charming game for something that challenges you to not die a screaming death at the hands of the dozens of zombies laying siege to your house.

There are minigames; there is a funny almanac to read; there are puzzles. You may get control of the zombies at some point. You can just chill in the Zen Garden. In sum, the game is absolutely filled with things to do, outside of the long main game. For $20, this is a great buy, although right now it can be found for $10 on Steam. For those of us with Macs, there is a version compatible with Intel-based hardware that launched alongside its PC cousin on day one. This is a trend we'd like to see continue, even if our PowerPC brethren howl in anger and frustration.

Plants vs. Zombies is filled with content and surprises, it's inexpensive, it runs on PC and Mac, and it's a version of the Tower Defense idea that actually feels fresh. The only downside is that for some the difficulty may take a while to ramp up, but it does get challenging as you progress and are faced with more, and tougher, decisions. This is a hard game to walk away from, and we're guessing the PC and Mac releases are only the beginning. This is a game that would work well on the iPhone, the DS, the PlayStation Network, and Xbox Live arcade; we can expect the addiction, just like the zombie apocalypse, to spread faster than we're comfortable with.

If you value your free time, find something else to buy. Just saying.

Verdict: Buy