Tamagotchi

Tamagotchi was a popular 90's Japanese toy. It's a handmade digital pet. Up until 2010,over 76 millions Tamagotchis has been sold worlwide. As of 2017,over 82 millions units has been sold. 
Most Tamagotchi are housed in a small egg-shaped computer with an interface usually consisting of three buttons,although the number of buttons may vary. 

Tamagotchi was created by Aki Maita for which she won the 1997 IG Nobel Prize for economics. It's a keychain-sized virtual pet simulation game. The characters are colorful and simplistically designed creatures based on animals,objects or people. It's up to players to raise the egg into a adult creature. The creature goes into several stages of growth and will develop differently depending on the care the players provide,with better care resulting in an adult creature that is smarter,happier and require less attention. Pets have a hunger meter,a happy meter,a bracelet mater and a discipline meter to determine how healthy and well behave the pet is. If the pet get sick,a skull icon appear next to the pet with a unhappy expression. The pet can die if sickness is left unchecked or if the players don't care of the pet. 

After that,they did a Gameboy game of Tamagotchi.

Tamagotchi also got 3 movies in total but also had a anime,in which I enjoyed when I was little.
My favorite characters were Mametchi and Memetchi.

The controversy..
During the 90's,children frequently took Tamagotchi to school because in the first two releases,a character could die in less than half a day if it did not receive adequate care. Concerns over class disruption as well as general distraction from schoolwork eventually prompted many schools to ban the product.