Here is a build I suggest for around the $1000. It is pretty similar to my Steambox/HTPC setup. It will run Civ5 and Xcom no problem (not to mention just about any other game).

http://pcpartpicker.com/user/CraZed./saved/sdZj4D

There are a few corners I cut like cutting out an overclockable mobo and CPU. I think you could also drop down the GPU to a R9 270X. Also you could go down on the CPU from a 4690 to a 4670 but the price difference is negligible.

If all you're looking to play is older games and strategy games, you can easily get a PC within ~$600-700. I will say this, though. if you have a budget of $1000, it might be worth going all the way just to see just how great PC gaming can be on the high end. I think you'll be surprised.

Anyway, for a medium end build that will suit you just fine ($660)-
http://pcpartpicker.com/p/fRxwK8
(Honestly, the video card is a bit overkill in this build, but if you wanna shave some more money off just go with a Nvidea 750ti)

For a build that will be worth every cent of your budget, and be capable of high end gaming ($985)-
http://pcpartpicker.com/p/gYKwK8

With either build, you will be able to play the older games and strategy games. The second build has the added benefit of being able to max out most games for the rest of the generation. Both builds have an SSD for the OS as well, so your PC will boot up and perform insanely fast.

If you have more questions, just ask.