UNITED NATIONS — Gaming is going green — and some of the biggest game companies hope players will, too. The companies behind PlayStation, Xbox, Angry Birds, Minecraft, Twitch and other video games and platforms pledged at the United Nations in September to level up efforts to fight climate change and get their throngs of users involved. The promises range from planting trees to reducing plastic packaging, from making game devices more energy efficient to incorporating environmental themes into the games themselves. “I believe games and gamers can be a force for social change and would love to see our global community unite to help our planet to survive and thrive,” Sony Interactive Entertainment CEO Jim Ryan said on the sidelines of the U.N.