“Pika. Pika pi, pikachu. Pi ka chu.” OK, maybe writing this story in Pika-ese isn’t a great idea. Still, it does remind us of an important point: one of the most popular video game characters ever created can’t say any words besides his own name.

Pikachu was one of the 151 Pokémon introduced in the original games back in 1996, which celebrates its 20th anniversary this week. He quickly became its breakout star, featuring prominently in the popular cartoon, movies, card game, and tons of merchandise. You saw him on everything: T-shirts to plush dolls and school supplies like binders and notebook. Pikachu has helped boost the Pokémon series to over 200 million games sold — and $1.5 billion in merchandise sales annually. The newest games in the series, Pokémon Sun and Moon, will come out this holiday.

So, why did Pikachu become so popular? Well, first off, he’s just an appealing character. Like classic cartoon icons such as Mickey Mouse, Pikachu is mostly made of circles. That roundness gives him a soft, inviting, and charming look. It’s hard to look at the little guy and not let out an “awwwww.”

Image Credit: The Pokémon Company

He was also a fun Pokémon to catch in the original games. Pikachu was one of the first rare Pokémon you could encounter. He would hide in Viridian Forest, an early location in the game that’s mostly filled with relatively useless Bug-type Pokémon. Pikachu, however, was Electric-type, which are incredibly useful against Water and Bird Pokémon. In the early parts of the game, Pikachu was a fantastic addition to your party, which is probably why so many players caught him.

However, Pikachu’s popularity really began to soar when the cartoon came out. While the show followed a similar setup as the original games, the main character, Ash started his journey with a Pikachu instead of one of the three starters players had to choose from (Squirtle, Bulbasaur, or Charmander).

Image Credit: Nintendo

“When they did the anime, they wanted a specific character to focus on. Pikachu was relatively popular compared with the others and potentially both boys and girls would like it,” Pokémon creator Satoshi Tajiri told Time back in 1999. “They heard a lot of opinions about this. It wasn’t my idea.”

It was a marketing decision, but it was one that paid off. Pikachu’s prominence in the cartoon boosted his popularity to meteoric heights. Nintendo even released a third version of the original Pokémon games (Yellow) that let players start their adventure with a Pikachu, just like in the show.

Image Credit: Macy's

He quickly became one of Nintendo’s most important characters, right up there with Mario and Link. He was one of the original roster members in Super Smash Bros., a crossover fighting game that features Nintendo’s most popular characters. He was front and center on all Pokémon promotional materials. He even became a balloon in the Macy’s Thanksgiving Day Parade.

Pikachu has become a merchandising powerhouse. Just look at how many items he appears on in the official Pokémon store. You can buy Pikachu notebooks, Pikachu key-chains, and even Pikachu knee socks. He even became a Volkswagen Beetle.

Even 20 years later, when you hear the word Pokémon, Pikachu is probably the first thing that comes to mind. Thanks to a combination of great design and smart marketing, he’s become an icon in gaming and, really, all of media.