I have been playing the shit out of "X-Com - The Enemy Unknown". I just got the Enemy Within DLC which is more like an expansion pack than a DLC, and I downloaded the mod "Long War" to go with it. Now, for those that don't know, LW adds a metric ton of things to the core game that adds to it like nothing you've ever seen. But it also ratchets up the difficulty from somewhere ground level to the fucking stratosphere. I did something I've never done in an X-Com game before in that I refused missions because they were basically unwinnable at my level of tech. I mean, I'm still rocking rifles that do minimal damage and I'm meeting creatures that one-shot me and I have to hit them 4-5 times to take down. And there's more of them than me. Oh, and they don't miss whereas my guys are like fumbling morons of ammo-wasting.
Sounds frustrating, doesn't it? Well, I save scum the fuck out of this game because you almost have to. Loving it, though.