I actually went back and finally finished XCom: Enemy Within a few weeks ago. I've had it for years but could never keep a good crew around to finish it. Civ IV was one of my all-time faves
Looking to buy Civ 5 and Xcom 2 in the new year. Anyone play either of these games a lot yet? Worth buying if they end up on the Steam Winter sale?
I recently bought both games and they are fantastic. Maybe i am bias though. I would say that Xcom 2 is more of an update on the previous version, the actual tactical war screen and strategy is pretty much the same, just new weapons, suits and a bit more options on how to build up the soldiers. The HQ is essentially the same as well. The difference is the world screen, you have a bit more variety of what to do and it is a little less repetitive. If you liked the last one, this is basically the same thing just slightly improved.
CIV 6 (i assume you mean the 6th version, the 5th came out a while ago) is also very similar to the previous version, but here there is a significant improvement in graphics, Nukes work differently now, there is also a bit more variety in the wonders and the "feel" to the game is much much smoother. There is a lot more variety in how you can run your nation as you can pick cards (they are called something else, forgot what though) which differ from each nation. Obviously the previous version came out ages ago, so it was expected this would be a significant upgrade.
Basically both games are upgrades, the concepts are essentially the same, just the newer versions are way more polished.