The beauty of virtual pet sites is that there's not one singular right way to do them. Besides the core feature of having pets, there's a lot of variability on what kinds of features a certain site might require as central, or relegate to the sidelines, or skip entirely.
When my site first entered closed alpha, it had the following features:
- Five pet species, each of which had several subspecies
- Ability for pets to grow from an egg to an adult in real-time (one to three weeks, depending on the species)
- Rewards for interacting with other people's pets
- Rewards for releasing pets into the wild
- The artifact summoning system, wherein players exchange resources acquired from interacting with and releasing pets for a chance at valuable items
- The town square, with a cooking system, a crafting system, a general store, and a wishing well that allowed players to exchange items for random other items of the same rarity
- Random events
- A gardening system to provide food for pets
- A rudimentary shop system where users could sell items to other users (which was completely overhauled before the beta launch)
- Building new rooms to serve as gardens, shops, or slots for additional pets
Notably absent from this list are many features that others have claimed are essential, such as minigames, forums, battling, direct messages, and auctions. Many of these were considered and intentionally not included in order to ease the need for moderators on the nascent site. Others are simply out of scope and do not fit into the long-term vision for the site.
Of course, this was a closed alpha test, and perhaps not indicative of what a full launch would require. But between the alpha soft-launch and the beginning of the open beta period, the only major systems added were more versatile user shops and the ability for players to decorate a room for each of their pets.
So, what do I think is actually needed for every pet site?
- The ability to personalize something. In my site, this is the furniture system, and the more recent addition of editable descriptions for pet rooms and user profiles, but this could also be a system for dressing up pets, an avatar customization system, or anything else.
- Something small to encourage people to check back regularly. Some examples of this include periodic releases of new pets or items, pets that grow to new stages frequently, or daily clicks to collect items. My site fills this niche with a set number of times per day that users can click on other people's pets, the gardening system, the necessity to feed pets every day, a recently-added store that stocks new furniture each day, and other things that have a one-day cooldown such as the wishing well.
- Long-term goals to work towards. There's only so long that users will keep playing on a site for the novelty alone; if they don't have anything to look forward to, it can get monotonous. This is something that I'm still figuring out on my own site: but so far, in the medium term, players want their pets to grow up strong so they can get rare forms or release them for a lot of resources, and in the long run, they may want to build additional rooms so they can have more simultaneous pets, obtain new pets of different species, or raise and release every form of their favorite species.
Every pet site I'm aware of has at least
something for each of these three primary niches. There might be other necessary niches besides these, but these are a bare minimum without which a pet site cannot function.
Edited to add: a fourth crucial niche is
interaction with other players. Otherwise, what's the point of it being a website rather than just something on the user's local machine? My site accomplishes this through user shops and the pet interaction system, but of course plenty of other interactions would be possible, such as PVP battling, forums, art contests, collaborative goals to work towards, or anything else that requires users to think beyond just raising their pets in a vacuum.