Rovio is shutting down its competitive multiplayer bird-flinger Angry Birds Friends for an hour tomorrow.
Why? It's for Earth Hour.
Yep, Rovio has teamed up with WWF (Worldwide Fund for Nature) to bring more attention to energy conservation.
So, expect it go offline for an hour from 6:30PM GMT onwards. It's up to you whether or not you participate further for turning all the lights off for that hour. It all helps, though.
There's also a week-long Angry Birds Friends Earth Hour tournament that will be ongoing inside the game. So, when the game comes back online, look out for details on that.