Verpets
Neopets, beloved as it is, also came with strict rules and a huge overhaul of features. To combat this, many other pet sites tried their hand at launching a more lenient game, one of which was Verpets. Verpets brought a lot of long desired features into their PHP pet game. Verpets allows users to have 8 pets, more if they buy slots. Pets are found in an RPG style overworld, battled, and captured. They have their own profiles that function almost the same as the user's. This means, pets can comment on each other's profiles, friend other pets, and even pick "companions". Paid content is interesting as well. Players can use custom pet designs or avatars for small monetary fees.
Unfortunately, Verpets userbase fizzled out. While the site still exists, it is only accessed by a few players daily (often less then 10). The site has not seen significant gameplay updates or features in years. Without an active community, "multiplayer" features are hard to enjoy.
Regardless, the art is incredible, and so are the pets! Here are my favorite designs: