Plants vs. Zombies, the latest crack-infused Oreo cookie from Popcap Games, is an excellent strategy game. It succeeds in essentially everything it sets out to do: It's approachable, it is indeed strategic, it's replayable and it's funny. As a strategy game, it may very well be a gateway drug which lures an entire generation of casual gamers over to strategy gaming, a genre that, like flight simulators, was once an everyman's pasttime, but has become a rarefied niche.

George Fan, the game's designer, should be proud. Unfortunately, talking to him made me realize how much I want the game he almost made. The game that Plants vs. Zombies almost is. Because Plants vs. Zombies is almost the best computer based non-collectible cardgame ever made.

George Fan isn't a household name among designers. His first game practically nobody ever played, despite having the excellent title of Wrath of the Gopher. But right after that he made Insaniquarium, a game about feeding fish that poop money, which you use to buy bigger and better fish. Oh, and you fight off aliens once in a while. Seriously.

And here's the thing about Insaniquarium: Yes, it's a "casual" game, one that got picked up by Popcap for the deluxe treatment, to be pawned off on people who don't consider themselves gamers as part of Popcap's stealth-rise to the multi-continent, millionaire-making giant it is today. But it's also really addictive, because it combines a few core mechanics that just don't seem to get old:

1: Resource development (feed the fish, buy new fish)
2: Resource collection (fish poop money)
3: Combat (aliens attack!)

Insaniquarium is a very, very simple game, a classic flash game that you consume in one sitting, and quickly forget. But because the mechanics are sound (and it sold well), it only made sense that Fan would want to get a little deeper. "Someone mentioned doing a sequel," recalls Fan, "and there were things I wanted to do with it that I didn't get to: I wanted to do something more defense oriented -- like buying fish that protected you well, if hordes of aliens attacked you." But ultimately the metaphor just wore thin. So, being addicted to tower defense mods for Warcraft 3, he shifted from fish to plants: plants seemed like a natural immobile "tower," and they would allow him to have a game where the towers had character, and could be funny. "So, what can attack you?" posits Fan. "Well naturally it would be the aliens from Insaniquarium. Now they're hungry for vegetables instead of fish!"

That's how the game we have now, Plants vs. Zombies, started. It was called Weedlings back then, and it was essentially a gardening game. A gardening game with aliens. But the problem was, the whole plant-nurturing gardening-game genre actually started to fill up. In the casual game space, gardening was the new black in 2005-2006. "That's where the zombies came about," says Fan. "I thought 'nobody's going to make a game where plants are going to fight zombies before I finish this game. And nobody has. So that's great."

In Plants vs. Zombies, the Insaniquarium paradigm is repeated -- the board's even similar, with a hand of "cards" at the top of the screen, fueled by resource (sunpower) collection dropped from a critical asset (sunpower-producing plants). Through the game's "Adventure Mode," players pre-select a handful of seed-packets, which they can use to plant different species of plants with different powers and different amounts of sunpower. The actual field of play is even more restrictive than the free-form aquarium: a 6 by 9 grid. It wouldn't take long for aliens to get across. "The grid is relatively small ... so you need a slow-moving antagonist," explains Fan. Zombies were the natural enemy to replace the fast-moving aliens from the aquarium assault. "Plus I think they're funny."

And they are. Plants vs. Zombies' core 5-8 hour game mode succeeds as much because of it's charm as its gameplay. The game introduces new plant types and new zombies with deliberate slowness, something I found tedious at times. But each level lasts only minutes, and almost always includes a genuinely funny punchline or a twist, and thus more often replaces tedium with joy.

It's this deliberate trickling that makes me long for the game that Fan almost made. By the end of the game, players have 48 plants at their disposal against 26 zombie types -- not an outrageous variety, but certainly as many as most real-time strategy games. Most of the time, you select 7-10 of these plants, and you can field your forces based on your collection of sunpower (every plant has a sunpower cost) and the recharge time of each plant (no spamming allowed). While this is a mechanic that's easily conveyed, it wasn't how the game started out.

"I didn't want it to just be a normal tower defense," recalls Fan. "I was teaching my girlfriend how to play Magic: the Gathering at the time, and that kind of inspired me to work in some of the things I liked about Magic. That's how the seedpackets came about -- I was trying to make it more like a card game."

And that's how he built the game the first time around. Players would have to make a deck of "cards" -- seedpackets in this case -- and those cards would be dealt out in real time. "We tested the CCG gameplay out, right after I joined PopCap," says Fan. " And the feedback was that people might not get it." And so the CCG version of Plants vs. Zombies was turned into a simplified minigame that still exists as an interstitial event in core game. Instead of buying plants with sunpower, they are simply fed to you on a conveyor belt.

This is the game I wish I could play. The irony of Plants vs. Zombies is that for a "casual" game, there is essentially no randomness in it. The field of zombies will vary slightly when replaying a level, but in practice, any given level will always feature the same distribution, no matter how many times you play it. The recharge system that dominates most of the game, while easy to understand, easy to explain, and perhaps easy to implement, leads to extraordinarily predictable game play. The "build order" for almost any set of 7 cards is almost always the same: Get resource production going while putting up a minimal defense, then build up quickly to withstand the big onslaught that will inevitably come at the end of the level.

A true CCG mechanic -- one that involves deckbuilding, distributions and just a hint of chance -- would add that extra element that would turn what is an excellent game into once-in-a-genre breakthrough. Is that sour grapes? Perhaps. Plants vs. Zombies is $10 if you pre-ordered it through Steam. It's $20 if you spend the maximum amount of money possible on it. The core game is tremendously fun, and the unlocked minigames and modes are deep, strategic, and have already eaten my brain for hours. But it's excruciatingly clear to me that there's an engine underneath Plants vs. Zombies that could have been even that much better.