Battlefield 2142 lost official online multiplayer support in 2014 with the shutdown of GameSpy, effectively killing the game. Now, fans have endeavored to bring the game back online and seem to have successfully done so.
Known as Battlefield 2142 Revive, the fan-led project has restored online functionality to Battlefield 2142, the futuristic shooter released back in 2006. According to stats listed on Revive's website, hundreds of people are playing at any given time, with the peak being just over 600 concurrent players. That's not a huge figure, but Revive has only been available for a few days, and that's enough to have multiple 64-player matches going simultaneously.
You can download all of the required files to play from the Revive website. That includes the game itself and its expansions, which raises the question of whether EA will allow it to continue operating.
Other attempts were made in the wake of GameSpy's closure to bring 2142 (and other games) back to life. Some were more successful than others, but Revive appears to be the most reliable way to play 2142 again.