On 15/12/2015 18:34, Oscar wrote:
My grandkid wants a "gaming" computer (and don't want to make the
same mistake again!).

Long ago, I bought a different grandchild a computer, which turned out to
not be able to run Call of Duty games he wanted to play (and Target
wouldn't even take the games back).

So I don't want to make both those mistakes again.

This time, I asked what games he wants to play, and he said he'd like
to play something called "fallout 4" which doesn't apparently work on
his playstation 3 we bought him a few years ago.

What do I need to look for in a Windows laptop that will play such games?

You asked about a "gaming" machine, and you got replies about it. They
explained why a dedicated gaming console would be better value for money
than a laptop.
That's all fine and dandy, but I wonder: is your grandkid going to play
all day, and do nothing else with that machine? Hmm. I guess they are
going to use it for lots of other activities too. So, maybe a computer
would not be bad choice after all, as long as you have the dosh for it