Over Nearly 25 million gardening enthusiasts have enlisted to fight the undead in Plants vs. Zombies 2 within two weeks of the game's availability, developer PopCap announced last week. The sequel has already surpassed lifetime sales of the original Plants vs. Zombies.

PvZ2's free-to-play business model is the central difference between the two versions, allowing players to get hooked on the game before they spend a cent on it. Hooked is about the right way to put it, too, given that over 81 million hours have already been spent on the game's unique take on botanical warfare.

PvZ2 is currently only available for iOS and will spread to other platforms "later this year and beyond."

Update: The text of this article has been adjusted to more accurately reflect PopCap's announcement, which is that Plants vs. Zombies 2 has been downloaded "nearly" 25 million times, rather than exceeded that amount.