Insurgency is a very cool middle ground between Counter-Strike and Arma, a CQ team based shooter from a Canadian dev team. They're having a free weekend on Steam right now as well as a 50% off sale for the game. If you like one shot kill FPSeses and keen attention to military-level detail it's definitely worth checking out.
I was surprised to see how much work has gone into the game since I first played it back in Early Access, there are a bunch of modes and maps and the presentation of the game is much, much slicker. So if you bought it a while ago and haven't tried it out since, the free weekend is definitely a good time to do it.