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But the flicking mouse causes pain. Literal pain in my eyes/headache causing strain.

I'm going to try out some of the fixes suggested here in the forums but I'm going to have to recommend people who've had any vision loss or who've got a photo-sensitivity...

... do not get this game. I feel like it might need a seizure warning but I"m not sure.
Unfortunately, Nox has that issue when running on modern machines and systems, and I'm sorry to hear you had a very bad experience playing it. Fortunately, though, it's something that is very easily solved, so I wouldn't go as far as downright telling people not to get the game, as it is one of the best "oldies" GOG has to offer -- and one of the most underrated and overlooked, as well.

If you're experiencing mouse flickering/disappearing, simply uncheck "Unlocked DX Surfaces" in the Options menu (accessed by clicking "Options", in the lower left Main Menu screen) and you should be good to go.
It defaults to unchecked.

When checked the screen renders nothing new except a flickering repeating series of mouse trail duplicates that would surely cause nausea had I not alt F4'd and dramatically dove for cover under my desk at the same time.

Trying suggestions in forums so far hasn't yielded results.

Compatibility Settings.
In game Settings.
Window size.
- Window
Mouse Settings.
One last thing will be to see if another mouse a non-Gaming mouse (I has a Razer) might somehow be better.

Ah great. Now I can't even get it to run imperfectly... time to re-install.

RECOMMENDATION. Do not re-check if "Unlocked DX Surfaces" is unchecked when you load the game.
Post edited November 21, 2014 by Ihear_BlueColors
If those fixes do not work, try submitting a ticket under GOG itself.

I had issues with La-Mulana and the kindly DEVs at GOG got right back to me and fixed it.

Sorry to hear you are having an issue with the game. If you can give it another chance once the mouse issue is cleared up I'd strongly recommend doing so. There is nothing quite like it around, truly the kind of gem that makes GOG such a great site.

Jeez Man >_< Go see a Doctor