PetPet Park (lost online MMO game based on Neopets; 2008-2014)
PetPet Park launched in October 2008 by Neopets and Nickelodeon Kids & Family Virtual Worlds Group.  and focused on the Neopets' companions, Petpets. The virtual pet website Neopets has had multiple spinoffs over the years, whether they were site-based minigames, or on various apps. Some of these include The Last Smiley, Neopets Mobile and PetPet Park.
Before it opened in October 2008, it started as a mini plot in Neopets, where Neopians would go on missions to help agents "make sure any Petpets crossing over to Neopia arrive at Petpet Park safely." 
Petpet Park was an isometric MMO, primarily focused on completing quests and character customization. Membership was an additional option for players looking to unlock more features, such as cosmetics and member-only areas.
The game was somewhat similar to Neopets, with players having the ability to customize and feed their virtual pets. There were of 9 species of Petpets to choose from as of 2014, but the game initially started with six pets: the Pinixy, Kassegat, Drym, Oukin, Dipni and Hifflo. The later three additional members only Petpets were the Puxa, Mumbat, and Bandalu. 
No playable versions of the game have surfaced since then, and in May 2017, Neopets stopped paying for the domain; the site's current state is an advertising page unrelated to Neopets.
There are currently no playable versions of this game; however, as of 2022, two groups currently is active in attempting to restore Petpet Park,petpet project x(started in 2014) and Petpet Park Rebuild (started in 2021)
A reddit user (u/neo_truths) made access to previously lost files available to ensure that not all features of the game are totally lost. (i.e., beta content, in-game code, etc.)
- Tales of Neopia (unreleased MMO game based on Neopets; 2008-2010)
- Neopets Movie (partially found production material for unproduced CGI animated film; 2006)
- The Last Smiley (found online Neopets platform game; 2004-2006)
- Neopets Mobile (found features of discontinued T-Mobile service; 2006-2009)
- Announcement of the opening of the game's beta. Retrieved 02 Apr '19
- Jellyneo page summarizing Petpet Park and its features. Retrieved 15 Dec 2022
- A post on a Neopets fansite about the layoff of many Neopets employees, after the acquisition by JumpStart. Retrieved 02 Apr 2019
- A list of news updates by Neopets in September 2014, including the announcement of Petpet Park shutting down. Retrieved 02 Apr 2019
- Petpet Park's current state at the moment. Retrieved 02 Apr 2019
- neo_truths' beta assets dump