Adopt Me!

Adopt Me! is a massively multiplayer online game developed by Uplift Games on the gaming and game development platform "Roblox". The original focus of the game was a role-play wherein players pretended to be either a parent adopting a child, or children getting adopted, but as the game was developed further, its focus shifted to being about adopting and caring for a variety of different virtual pets, who can be traded with other players. "Adopt Me!" has been played a total of 20 billion times as of March 2021. Uplift Games, the independent studio behind the game employs roughly 40 people and earns 50 million dollars a year, mostly from microtransactions. The game was averaging 500,000 concurrent players as of January 2021, making it the most popular game on "Roblox".
Gameplay.
"Adopt Me!" revolves around adopting and caring for a variety of different types of pets, which hatch from eggs. Some pets can only be purchased with Roblox's virtual currency, Robux. Pets are grouped into 5 classes, based on rarity and cost. These groups are common, uncommon, rare, ultra-rare, and legendary. Once hatched, pets grow from their starting status as newborns, growing up into juniors, pre-teens, teens, post-teens, and eventually becoming full-grown. If a player has four fully grown pets of the same type, they can combine them to form a "Neon" pet, and four fully grown neon pets can be combined into a "Mega-Neon" pet. Purchases within the game are facilitated both by Robux, and through "Adopt Me!"s virtual currency, simply called "Bucks". Bucks can be earned by fulfilling the needs of a pet, such as eating and drinking, among other methods. In "Adopt Me!" players can also adopt kids, and roleplay with other users. 
History.
Before 2018, "Adopt Me!" had been solely about adopting children, in line with several earlier "Roblox" games with the same concept. 2019 was when the game added the feature of adoptable pets, which caused the game to rapidly increase in popularity. "Adopt Me!" had been played slightly over three billion times as of December 2019. As of July 2020, the game had been played upwards of ten billion times. In March 2021, "Adopt Me!" reached 20 billion total plays.
Players.
The highest number of concurrent players "Adopt Me!" has achieved is 1.92 million. Around a third of "Roblox" players on the Xbox One play "Adopt Me!". Due to the presence of microtransactions in the game and the target demographic being young children, there have been instances of children spending large amounts of money on "Adopt Me!", including one particular incident where a child from Australia spent $8,000 AUD ($6,348.88 USD) on the game. 
Whenever there is a major update to the game, the number of players playing can triple, which can cause platform-wide disruption on "Roblox".
Scams.
Due to the high cost of pets within the game, with some rare pets selling for up to US$100, a large subculture of scammers have risen within "Adopt Me!". Buying pets with real-world currency is against both the "Roblox" and "Adopt Me!" terms of service. As the primary user base of "Adopt Me!" is on average younger than the rest of "Roblox", they are especially susceptible to falling for scams. 
One of the most common ways in which scammers carry out their operation is through "trust trades", in which the scammer manipulates the player to trust them into trading a rare virtual item, promising to give the item back. The scammer will then leave the game with the victim's virtual item, leaving the victim with no way to get it back. 
On November 5, 2020, "Adopt Me!" released several new features focused on combating scams, including the introduction of "trade licenses" that are required to be earned before one can trade pets above uncommon rarity, the amount of pets you can trade, and the addition of viewable trade history and the addition of notifications to the player if the game detects a markedly unfair trade.
Reception.
"Adopt Me!" has received generally positive reviews from critics. "PCGamesN", in an overview of what they considered the best games on "Roblox", described it as "cute", and compared it positively to the "Petz" series. Forbes described "Adopt Me!" as a "nice and gentle" game. Some Roblox users have criticized the game, due to it causing Roblox servers to occasionally crash when an update launches.