If that Pentium G600 really means G5600, then I think that is an excellent budget processor.
It needs a 300 series motherboard.
I just built something similar for my grandkids using a GTX1060.
Make that ram a 2 x 8gb DDR4 kit.
Buy a quality psu, 450w is fine.
I will never again build without a ssd for the "C" drive. It makes everything you do much quicker.
120gb is minimum, it will hold the os and a handful of games.
But, many things default to the "C" drive.
When a SSD nears full, it will lose performance and endurance.
240gb is the recommended minimum.
If you can go 240gb, or 500gb you may never need a hard drive.
You can defer on the hard drive unless you need to store large files such as video's.
It is easy to add a hard...