Deus Ex

Vert- by default. Set FOV for Hor+. Use Deus Exe for automatic FOV handling. Glide renderer may not work for this; choose Direct3D, Direct3D 10, or OpenGL. The included Direct3D renderer will not work for resolutions higher than 2048x1536.

Some higher resolutions may have HUD scaling issues. Use Deus Exe to adjust HUD scaling or set it manually.

Manual steps:

Open user.ini. Find these lines:

DesiredFOV=75.000000
DefaultFOV=75.000000
Change the values to set your FOV to your preference. I recommend 85 for 16:10 resolutions and 90 for 16:9 resolutions.

Choose your resolution in-game. Alternately, go to \system and force in deusex.ini:

FullscreenViewportX=xxxx
FullscreenViewportY=xxx

If your resolution constantly resets in user.ini:
First run the game and select a 4x4 digit res from the video options menu, i.e 1600x1200 or 1280x1024. Then you can edit user.ini and your new resolution will stick.

To the best of my knowledge, the FOV setting affects every part of the gameplay that uses the 3D view. 2D gameplay elements, mainly the extensive screens used for things like managing inventory, augments, and logs, are scaled correctly.

However, in the cut-scenes, at some of the higher resolutions, parts of the subtitles can get cut off. Dialog is all spoken, so this shouldn't hurt playability.

The cut-scenes are rendered ingame. Unexpectedly, they are anamorphic, independent of your FOV setting.