Brothers: A Tale of Two Sons

UE3 game, Vert- FOV... Use the tried and true FOV key method:

%USERPROFILE%\Documents\my games\UnrealEngine3\P13\Config\P13Input.ini

[Engine.PlayerInput]
Bindings=(Name="T",Command="FOV 106.26")

Run the game and press T to fix the FOV.

See MM Solution below for more info.

Same method, use FOVCalc to determine the best FOV for any aspect ratio.

AR, recommended FOV :
16:9, 90
21:9, 106.26

15:4, 129.27
48:10, 139.35
48:9, 143.13

Chapter 4 telescope bug:
At one point during the game, the brothers can use a telescope. Any custom FOV will render the telescope's zoom unusable, which renders a certain achievement impossible to get.
Luckily there's a checkpoint right before the telescope, so here's a workaround:

1. when you've reached the telescope, quit the game. (Feel free to look around the scenery, but fixed FOV is way too high and zoom is broken.)
2. run the game, do NOT press FOV key !
3. load last checkpoint and use the telescope all you want. Default FOV is Vert- but native zoom functionality is restored.
4. press T when ready to continue the adventure.

FYI default telescope FOV is 30 in 16:9.