Operation: Petpet Park is now over! You cannot complete missions any longer.
About Petpet Park
So, what is Petpet Park? Glad you asked!
Right now, we know that Petpet Park is going to be a new feature on Neopets that will be expanding into the world of Petpets. You will be able to select one of six new petpets to play with. (We're assuming old petpets won't be available.) Once you choose a petpet, which you can do even if all of your pets already have a petpet attached, you will be able to dress it up, paint it, train it, and play games with it, and once you think it's good enough, bring it to the Park to play with the other petpets.
Here's an interesting quote from the Editorial with even more details:
Oh beneficent TNT, deliver unto me an answer to this message. The users cry out in despair over the release of your latest feature, the grand Petpet Park, and have somehow got the notion that it will be a pay-to-play addition to Neopia, akin to the NC Mall. Silence their fears, quell their despair, and deliver unto them your divine answer so that the Petpet Park boards may return to peaceful chat and remain not as repeated curses under your name. ~reclusiarchmikelus
Hark, for we heed their cries and answer thusly, child of Neopia.
Without giving too much away early, we created Petpet Park as a world solely dedicated to Petpets and the Neopians who love them. (We very frequently hear things like, "it would be way cooler if the Petpets were more interactive," so we wanted to oblige.) :) The Petpet Park world uses Neopian characters, settings, and history, so it's still part of the Neopets universe, but it's separate from the site itself. Think of it like... any of the video games we've made (and ones will soon be releasing! *shameless plug*). They're set in Neopia, feature familiar characters and lands, tell Neopian stories, and we dedicate whole sections of the site to letting you know all about them, but they aren't actually part of the site itself. You wouldn't spend your site Neopoints in your Neopets: Puzzle Adventure DS game, for example. Those video games are on their own, self contained. Petpet Park is pretty much like that. (Only it's online and you don't need a game console, but you get the idea!) :)
And yup, it will be free to play. Everyone will have access, and there will be extra things you can purchase with Neocash for use within Petpet Park, just like you can purchase things with Neocash to use on Neopets.
So, the Grand Opening Celebration that you see now is an introduction to the world of Petpet Park. More info on Petpet Park itself is coming soon, and there might even be a small mini-plot starting possibly next week, maybe, but don't tell anyone we told you. :P
From Neopian Times, Issue #357, published August 29, 2008
Once Petpet Park is fully released, there will be a whole bunch of activities to do. From what the editorial says above, it sounds like its own separate site entirely. Perhaps a 3D world? :O We really have no clue at this point, but it sure sounds like it the way they put it. ;)