It's time to take aim at those dirty, noisy snowmobiles that have been threatening the health of humans and animals in Yellowstone National Park. And what better way to do that than throw a few snowballs at them? In The Bear Necessities, a game on the National Parks Conservation Association's Web site, you are a bear trying to survive the ingress of obnoxious snowmobilers. Using the mouse to maneuver, players dodge snowmobilers and fire snowballs at them to stop them from destroying the habitat. But even though the cartoon bear in the game is adorable, he's not invincible. If the bear is run over too many times, he dies, ascending into the clouds wearing a halo and playing a harp. At the end of the game the NPCA, which has fought to end the use of snowmobiles in Yellowstone, encourages people to take action because "real bears can only dream of protecting the national parks from the noise and pollution of snowmobiles."