Just as a note, Jotun is 64-bit only even though the notice only shows up if you click to show requirements for other OSs, isn't listed under those for your (or any) OS. Only checked that now, after installing and confirming the issue someone else also pointed out, as I expected it to say "64-bit only" next to the OS list if that was the case. So nothing for me to do with it, but thanks regardless.

I tried that but didn't help.

Suggestion: Squeeze off a bit of your hard disk or get another hard disk and install Linux on it and then you can run Jotun and some other games just fine, if your hardware supports them of course.
Did you click on the banner, while logged in, on the front page? Just making very sure.

Off topic:
I have one major problem with the Linux ecosystem at the moment, made painfully obvious after throwing Mint on my old computer last autumn while this was being serviced: No application level firewalls. And no willingness to make any, because "that's not needed on Linux". Only found a few complex and complicated security solutions that may have also included that but along with a whole slew of other things and one that somebody made and which seemed to fit the bill but which hadn't been updated in a while and, according to posts I saw, didn't work on recent kernels. Well, I'm not going to use a computer without that sort of control and monitoring of what connects where and when.
Otherwise, just throwing myself into Mint as I did for those 2 weeks or so then, quite liked it. But yeah, will never run it on a computer I'm actually using normally without that, period.

At some point Microsoft started allowing the customers to freely choose between 32 and 64bit versions when installing Windows. All I know is, it was after Windows 7. Maybe you can switch to 64 bit? I guess that would mean a complete reinstall, so quite a lot of work. IF you do that, make sure there are 64bit drivers for your computer's hardware and your Windows version!

I agree the common Linux firewall is rather basic but at least it is something.
You CAN block all traffic and thus allowing you to play single player games ;-)

I am just trying to help you to be able to play your game.

-----
When on Linux: mumble mumble this works so much better on Windows.
When on Windows: mumble mumble this works so much better on Linux.....

I have a retail copy, can install whichever version I want, but installed 32-bit since there's no point in 64-bit with 4 Gb of RAM and integrated graphics, higher memory use and no more memory to gain. And definitely not reinstalling for anything anyway, much less for a game I was really just trying out.
And I meant what would make me seriously see Linux as a viable OS for regular use. I know you can block everything, or everything except a list of exceptions you can create, but that's not a viable option for regular use, need stuff that detects connection attempts and if they don't match existing rules offers information and allows me to choose whether to allow or not and under what terms, and also allows me to monitor what's connecting and where and what it does.
Don't exactly care to play it, installed it more to check that report really, since there was no visible notice so I thought it SHOULD work.

Was Galaxy bundled with Jotun? I didn't have Galaxy, then I downloaded Jotun and now I do...

No. Just installed it earlier (and then uninstalled it due to it being 64-bit only, as I say in the previous comments), no Galaxy, not even some files in the game folder or registry entries left over.

Jotun is probably one of the "100+" games that come with Galaxy if you download the regular installer. If you don't want to have Galaxy on your machine, uninstall it. I haven't installed a single game using the browser ever since I got Galaxy but, next time, just to make sure, when you download a game off of GOG and you're not sure whether it comes with Galaxy or not, before downloading check if a game has "Classic Game Installers" in the drop down menu and download that instead, since it's Galaxy-free.

[EDIT] Cavalary just confirmed Galaxy isn't bundled with Jotun, so you probably downloaded an installer with Galaxy via some other game.

I don't know, as I usually use galaxy to install my games since it released a stable version, but I can still use my gog downloader if need be! The important thing is that the game installs/runs independent from Galaxy unlike the other shitty DRM-infested mandatory game launchers!

When is the last time you used it?

If you ever find a solution to your problem, please tell me. I have Win 7 in my desktop but after MS went the spyware OS route I swear this will be my last windows OS. Once this hardware gets too old I'll have to migrate to Linux and then I'd have the same problem you have.

(As per Themken's advice I'm thinking of buying another HD and installing Linux on it to get used to it to ease the OS transition. I guess I'd better start soon)

He meant a solution for an application-level firewall on Linux.

DOH! I am tired.... bRaIn No MoRe WoRk :-(

apologies