How good should games be playable in a year? You want them to play on highest detail level or is mid range OK for you? There is no cheap and ultra powerful

. You can e.g. go for AMD, which is cheaper than intel but imho (and this is just an "imho", not a de-facto-statement!) you are longer happy with an intel (bought an i7-2600k when it came out (approx 7 years ago?), a friend of mine got that from me when I upgraded and it still plays all the games!).
But of course, Simon is right on the graphic card part. I forgot that the graphic card pricing is atm a bit insane because of all the crypto mining bullshit going on.
I would recomment shooting for a PC with an intel i5 of the newest generation (i7 would be overpowered, I only got that because I even compile my own Operating System (gentoo linux), otherwise I would have gone for the i5). That should be enough CPU wise. Then I would shoot for a Mainboard that is capable of SLi or Crossfire (First is nVidia, second would be ATI), whichever you prefer and buy a Graphic Card like the GTX 1070. Then shoot for 16GB or DDR4 RAM. That should make you happy a few years.
Then you need the stuff around that. You can take whichever case you like best (I use the 20€ ones, they are enough for me). You should only check if the Mainboard Form Factor is supported (shoot for an ATX compatible and you are fine, this also would fit smaller ATX ones like ?ATX).
Then look at the components and the TDP value, which means Thermal Design Point and gives you a clue about the maximum amount of Watts your components take. Sum, them up, multiply it with 1.2 and then you have an approx of the size of your power unit. Note: Its best to be at about 80% of its capacity to achieve the best efficiency.
Also take whatever drives you need, e.g. a BluRay Drive or a DVD Burner.
Then the last part would be the cooler. This is a bit of a philosophy. Should it be quiet? Should it allow overclocking, etc, etc. If you do not want to overclock and the noise does not matter, then you can simply take the one that is bundled with the intel. At work we have i7-7700 running with them at 100% cpu usage and they are cool enough. If you want it very cool and very silent, shoot for an Noctua NH-D15, but take a note that you need a case that can fit that.
That are some tips, of course not all. Ask if you have any questions.