What's your budget, and other than a 12 year old game that most pc’s made in last 10 years would run. What other games or software do you want to use?
CPU's / RAM
I would strongly recommend against anything AMD that is not AMD Ryzen their single thread performance really sucks and would hurt gaming performance greatly.
As for intel anything 4th gen or better would be good. 4th -> 7th gen i would aim for i7 as they are 4cores/8threads for 8th gen+ i5 would be fine as they are 6core/6threads.
I used to have a i5 2500K (2nd gen 4c/4t) and that struggled with FarCry 5 (frame hitching and crazy fps drops), it was much better with the i7 2600K (2nd gen) but not perfect (hence suggesting 4th gen+)
For system RAM I would recommend a minimum of 8GB and preferably 16GB for more modern games, If your going AMD Ryzen ram speed matters and for that i would aim around 3200MHz. For intel speed matters much less.
GPU's
I have always been somewhat of a Nvidia fanboy on this front, their drivers tend to be better and maintained/supported for much longer. Although their current pricing really does suck and is obviously them exploiting their market dominance and the knowledge learnt about what some people will pay during the crypto mining boom.
On the GPU front the more you spend the more fps you will get, If going for nvidia aim for 10series or newer and use comparison sites to figure out your best bang for buck. I'm currently running a 1070 8GB and that comfortably runs all games in High at over 40/50fps. (I want a 2080ti but price is extortionate and I'm not willing to pay it)
for GPU RAM i would recommend minimum of 4GB but 6/8 GB will get you higher settings in more modern games.
Storage
For the system drive an SSD is a must to have to pc booting quickly and feeling snappy during use. 250GB minimum is recommended, you can get away with 120GB but its very easy to quickly fill this up, For SSD's I prefer the samsung's for performance/reliability and warranty.
As more modern games are becoming huge (50GB+) 250GB is not going to cut it for having many games installed, so i would also recommend a secondary Hard Drive 1TB or more and make sure it spins at 7200 RPM.
Hope all this information helps you find a good value pc with a fun gaming experience,
generaljoey: I'm currently running a 1070 8GB and that comfortably runs all games in High at over 40/50fps.- these still are around £350