Back in 1996, a pair of relatively simple games about catching and raising a myriad of fantastic creatures was released to the Japanese public. The creator, Game Freak, would soon discover that it had captured lighting in a bottle as it spread worldwide and became one of the foremost gaming empires.

This game was titled Pokémon. More specifically, Pokémon Red and Green (later adapted to Red and Blue in the American release) propelled the series into pop culture stardom, as the series’ namesake “pocket monsters” captured the hearts of children around the world.

This year, Pokémon is celebrating 20 years of games. The brand, having now released over 50 games after the original two, made four billion dollars for Nintendo in 2014 alone.

Having originally included 151 Pokémon, the series now boasts an impressive 721 unique monsters, soon to expand yet again with the December releases of the games Pokémon: Sun and Pokémon: Moon. With such a varied roster it is easy to see how everyone could find a favorite.

Not much is known about the news releases, aside from that they are set to release in winter on the Nintendo 3DS.

Although popular, Pokemon has not been entirely without its share of controversy. The game’s core mechanic of catching and training what are essentially animals has been a lightning rod for complaints from PETA. However, these issues never gained any ground based on their exaggerations, and the vast majority of people see the games as fine for players.

A significant portion of the franchise’s success lies in how it holds customers. Professional tournaments for the games, such as the Pokémon World Championships, are frequented by people of all ages.

There are entire communities dedicated to the study of the game’s mechanics. Pokemon games’ inner workings are actually fairly deep, and many players also choose to host their own private tournaments. The community comes up with strategies and teams that work well, somewhat like chess.

Most of all, the game’s nostalgic nature brings people back year after year. Someone who liked Pokémon as a child will likely come back every so often, buy the new game and spend another few dozen hours pruning and training a new collection of creatures.

The game’s way of capturing imagination and allowing so much variety is what made it so successful throughout its 20 years of operation. It’s not just the games, but the people around them that make Pokémon special. Hopefully, the games will make it another 20 happy years.