Zoo World 2: Will this sequel breathe new life into RockYou's zoo game?

When interest starts to wane in a Facebook game, most creators will launch a big, fancy in-game feature designed to keep players coming back for more. And, it seems to work, at least for a while. FarmVille got a big boost when it rolled out a second farm set in the English Countryside and FrontierVille's upcoming Pioneer Trail expansion will likely do the same.

RockYou's taking a different tact with its zoo simulation game, Zoo World, which was one of the most popular games on Facebook about a year or so ago. Instead of launching a big add-on to the game, RockYou rebuilt the game from the ground up and launched it as a sequel -- Zoo World 2 -- which is now live on Facebook.

A side-by-side comparison of the two Zoo Worlds shows that the new game has amped up the graphics and has built in more ways to customize your zoo to your liking.

zoo world 2

rockyou zoo world

Pretty graphics aside, Zoo World 2 also runs much faster than its laggy predecessor and employs a new energy system, meaning it now costs energy to feed and breed animals and to harvest kiosks for cash. Like any other Facebook game that uses energy, once it runs out, it will refill over time or there's the option to pay real-life cash to fill it up on the fly.

There are still plenty of similarities between the two games, such as the ability to harvest and breed animals and a series of quests, which direct you to do things like 'Buy 1 Animal' and 'Breed two babies,' and help drive the game forward.

Right now, the original Zoo World is still alive and kicking (go here if you want to play it), and there's no word yet whether RockYou plans to keep it around, or if it will eventually be phased out in order to drive players to the newer game. In the meantime, we'll see if Zoo World 2 has what it takes to put this zoo simulation game back on top of the Facebook gaming charts.