Aftercharge is a 3v3 FPS in which a team of robots, who are invisible, tries to make life miserable for a team of guards, who are invincible. It was announced in mid-2017, and with a full release set for tomorrow, developer Chainsawesome Games has released a narrated gameplay video explaining in detail how it all works, and how you can (hopefully) avoid being terrible at it when you first start playing.
The underlying concept is simple enough: The robots must destroy "extractors" that provide power to the guards, while the guards have to knock all three out. But special abilities and tactical considerations make it a more complex game than it might first appear. Fallen robots can be immediately revived by their fellows, but that exposes them to being knocked out themselves. And while knocking out extractors is the name of the game, planning ahead is important: A single, undamaged extractor is very difficult to take down, and forcing robots to concentrate their attacks in a single location makes life considerably easier for guards.
Teamwork seems crucial, particularly for the robots, which could prove frustrating for pickup games where players are thrown together at random. But if it can achieve and maintain a critical mass of players, I can see it being a lot of fun, too—a distinctive and fast-paced alternative to the usual "guns for everyone" online FPS action.