Community Challenges were one of our favorite features in the original Plants vs. Zombies Garden Warfare, and we wanted to bring them back for PvZGW2. However, like everything else in the game, we didn't want to settle for how we had implemented them before - we wanted to make sure they were Bigger. Badder. BIGGER than ever!
To better understand the spirit of cooperation, the Gnomes have developed the Progress-O-Meter, which you can find in front of the Town Hall in the Backyard Battleground. When a Community Challenge is activated, you'll be able to see what the goals are, and see how much progress has been made in real time, including your personal contribution. As more goals are completed, the prizes get even better - and the harder the challenge, the greater the rewards.
You can always check the progress on the community challenges page of our site, as well. In fact, you should head over there now to learn about the new challenge that started today!