spam messages

Could it be a coincidence I'm getting nasty spam messages after downloading a game from a site(I don't think I'm allowed to say which site but it,s popular)the game is 1954 Alcatraz.I want to stop them but don't know how.How does this stuff get into my computer.This is the first time in 15 years.Is anyone else having this problem?

Not sure what you mean by "spam"
Do you mean unwanted email?
Or are these pop-up ads that pop up any time and not email.

If you're talking about email, it's probably nothing to do with a game you just downloaded. There's usually a delay between when your email address was sold to spammers and when the spam starts.

If you're talking about pop-ups that appear at any time, those could have been installed with a game, depending on where you got the game from.

I Googled
"1954 Alcatraz" download
and the game is available at GOG and Steam. If you got the game as a "free" download, it was likely infected.

You can try to get rid of the infection with MalwareBytes. Check your Add/Remove Programs in Device Manager to see if something is there. If the messages only come when you're using your web browser, check your browser's add-ons list and delete your web cache.

I got the game from GOG but it wasn't free.I mean unwanted mail,very naughty in spam.I don't see anything to remove so I'll get someone to block this for me,very disturbing,

I feel quite confident in saying that this problem has nothing to do with your GOG download.

I agree with Marian. This has nothing to do with the GOG download. I get that stuff every now and then too. Lucking my ISP spam filter picks up most of it and it doesn't get downloaded to my computer.

O.K.Thanks all.