>>34203733Overgrowth.
The Pokemon card craze was insane at my school. I'd say at least 70% of the kids seemed to have them, and nobody knew or cared to learn how to actually play the game. It was all about collecting and trading. Recess and lunch was devoted to walking around and scouting for cards you wanted. In hindsight it was just ridiculous how much it took over. Even the girls were into it.
It lasted well over a year or so before it started to lose steam, too, and even then it was pretty popular. I mean they came out when I was in Year 2 (8 years old), and were still a common sight even in Year 4. It wasn't until Yu-Gi-Oh cards arrived that they really started to die off.