The three contemporary virtual pet games I'm attached to are My Singing Monsters, Marapets and Subeta. I should also mention Neopets but it has lost its previous popularity
Neopets has lost some of its popularity from years ago, but it still remains one of the biggest and largest pet sites.
There isn’t a single pet site that is putting up bigger numbers than them, as Neopets is a global powerhouse. They have merchandise in various stores and they’ve averaging 400k+ monthly daily logins. However, other pet sites average about 1k-2k daily logins. It will take a lot for other pet sites to take over Neopets’ popularity in terms of users and becoming a global name.
As it stands, Neopets over 200 millions users where Marapets probably has over 5 million users now. Lioden has over 500k users and Flight Rising may have over 500k users as well, but there may be some mobile pet games like My Talking Tom that have millions of users as well. Subeta has close to 200k users.
However, most pet sites aren’t known as a global brand yet, but it can happen. Especially with a media push or advertising campaign. Neopets also has a habit of launching press releases. Pet sites can do this as well, which can help them get a lot more traction and visibility in the news(media).
Roblox and Fortnite are probably the only two games that take the cake against Neopets. Club Penguin and Moshi Monsters were just as big as Neopets in their prime though.