They are doing a free weekend for this game on Steam this weekend.
Just an overview, I still play this a few nights a week. Have put over 200 hours into it and greatly enjoy it. The destruction really makes it a unique type of FPS. To me it's one of the few cornerstone games I wouldn't uninstall from my PC, along with CSGO, Diablo 3, and a few other select games. I'd highly recommend trying it to anyone who may have had any interest in it. One thing to mention though, similar to a lot of free to play weekends on games, it tends to draw in the hackers. Hacking is pretty minimal normally, I have only ran into a handful in my 200+ hours, but this weekend there are a lot of people trying out hacks.