Warframe's Empyrean expansion got a new trailer at The Game Awards tonight, and it also delivered a nice surprise for PC gamers—the expansion is live on PC, right now. 

In Empyrean, you can customize and pilot your Sigma Series Railjack battleship in four-player co-op. We first heard about the ambitious Empyrean expansion at Tennocon last year, and learned more this summer

You can play Empyrean solo, too, but it's really designed for a full four-player crew, though 2020 will bring updates more suited for solo players. There's also a free flight mode where you can practice piloting your Railjack without having to do battle.