Since you don't specify your operating system, I'll post some links for you to go to:

Take a look at this post: https://www.gog.com/forum/arcanum_of_steamworks_and_magick_obscura/windows_8_solved/post51

Also, check out this post: https://www.gog.com/forum/arcanum_of_steamworks_and_magick_obscura/win_81_arcanum_wont_launch/post8

And this: https://m.reddit.com/r/arcanum/comments/297apm/how_to_make_arcanum_run_in_windows_81_also_works/

Also, did you try the unofficial patch? If not, give it a try, it may help you.

If all else fails, just contact support. ;)

Os is windows 10.
Additional tested workarounds:
-Disable antialiasing
-unofficial patch
-window mode

Nothing works so far...

Have you already installed the old DirectX9 components from here:
http://www.microsoft.com/en-us/download/details.aspx?id=8109

Run the file and extract it to a separate folder.
Then go there and start DXSETUP for installation, so your system gets the old DirectX components as well. Your current new DirectX version won't be affected by this.

The game needs to think there is a keyboard + mouse attached.
3 & 5 are unnecessary.