People have played it successfully at 1920x1080
ex:
http://www.rpgcodex.net/forums/index.php?threads/arcanum-high-resolution-patch.31632/#post-740574 Your problem seems similar to this person's:
http://www.gog.com/forum/arcanum_of_steamworks_and_magick_obscura/must_have_arcanum_fan_patches_widescreen_and_more/page13 wizzyendor123
Two related issues: Aspect ratio & glitching at the games opening menu.
My native resolution is 1920x1080. I've installed Drog's UAP and Hi Res patch. I have tried several different resolutions with said patch, but the game screen never scales. I will play any game regardless of graphics. But playing this only using a 1/3 of the screen is just silly. Here is my caveat!! = Apparently my laptop routes the Nvidia graphics through Intel graphics properties(?) So to Fix Scaling, I have to use the Intel menu. My options with the Nvidia control panel are limited. And with the Intel menu, I have no fix scaling option at 1920x1080.
So when I leave my computer resolution as normal, the game looks fine, just 4:3. When I try different 16:9 resolutions with my graphics properties, matching those I set with the high res patch, the game screen looks like a Jackson Pollock. And I have yet to see the game go WIDE!! Under any circumstance.
Hopefully I'm missing something obvious. I've scoured forums but have not seen anyone mention my specific little problem. I really want to play this tasty game, so I come to you with hat in hand. Thanks for your time.
Spex: Windows 8aaaaate / i7 / geforce 770M / bla bla bla
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Maybe send a personal message to wizzyendor123 and see if he found a solution.