Have you caught them all yet? With six generations of video games and more on the way, Pokémon popularity shows no signs of slowing down as it celebrates its “Sweet Sixteen” birthday here in the United States on September 28.

Pokémon Red and Blue Versions (originally Red and Green in Japan) released for the Nintendo Game Boy handheld system almost immediately kicked off a worldwide Pokémon craze. Children and adults alike were hooked on the game, which emphasized collecting as many Pokémon as they could in addition to simply battling with them. The story and its goals were simple: raise your Pokémon, collect all eight Gym Badges, defeat the villainous Team Rocket, collect all 150 Pokémon, and become a Pokémon Master. The simple rock-paper-scissors style of play during the battles made it easy and accessible for new gamers while still being complex enough for seasoned roleplaying veterans.

Sixteen years later, not a whole lot has changed in terms of the game play style itself, but the series has undergone a number of improvements as technology has advanced. For example, what was originally a strictly 2D environment now features fully 3D renderings on Nintendo’s latest handheld, the 3Ds. Every new release in the series continues to sell spectacularly well. The franchise as a whole has moved more than 245 million units worldwide, making it one of the bestselling game series in history.

The games are hardly the only collectible aspect to this mega-franchise, though. The Pokémon anime series (which also debuted 16 years ago this month on September 8, 1998) has churned out more than 850 episodes and 17 feature length films. And the Pokémon Trading Card game, which remains Nintendo’s strongest link to its roots as a card company, has 60 different unique sets of cards. First edition, graded cards from the early sets can often fetch as much as a couple hundred dollars in auction, depending on the condition. And that’s not even touching on the immense amount of toys, figures and other collectibles that Pokémon spawned.

What seemed like a fad in the late 1990s has become a mainstay in video games and general pop culture. Sixteen years later, you still gotta catch ‘em all!