In February, hundreds of people gathered in Uonuma, Japan, to take part in one of the world’s biggest snowball fights. The annual Koide International Snowball Fight is an epic battle, and the last team standing wins.

The rules of the event are simple. Two teams of five people throw snowballs at each other for two minutes. Whenever someone is hit, points are awarded to the opposing team. Then the next pair of teams has their fight, and so on. In the end, the team with the most points wins. The prize is a bag of rice, a specialty in Uonuma.

“Put simply, you make snowballs, throw them, score hits and the (team with the) most points wins,” head judge Takuya Kitsu told Reuters.

Participants take their snowballs seriously, but the event is mostly just fun. In fact, teams must dress in matching colors or even costumes—and according to the rules, the sillier or more original, the better. 

In Japan, snowball fighting is a sport that’s regularly played in the country’s colder regions. There’s even a movement to add the sport to the Winter Olympics. Kitsu says snowball fighting is a great way to get through a time of year that can get gloomy, especially for adults.

“The snow can be a nuisance. It’s a hassle,” Kitsu told Reuters. “So we hoped we could turn it into something fun by starting these snowball fights.”