Fix available from the PC Gaming Wiki Community Files (search there).

New Solution: Download this MOD Star Wars Republic Commando Fix. It adds options for higher screen resolutions and a FOV-Slider to the menu and you can play the game even in 4K.

And the HUD Solution Republic Commando: Widescreen Hud Fix

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Old Solution: This is a two-part edit that includes both an .ini edit and a hack.

Resolution INI edit: Go to --> ...\Star Wars Republic Commando\GameData\Save\system.ini

[WinDrv.WindowsClient]

FullscreenViewportX=2560

FullscreenViewportY=1440

After you have edited the .ini file, right click on it and go to properties. Tick the box "read only" and apply.

FOV hex edit: Go to --> ...\Star Wars Republic Commando\GameData\System\engine.u

Search for this hex values: 00 00 AA 42. There will a couple instances. Each instance will need to be replaced with the value of your desired FOV.

The default floating point value for Republic Commando is 85 degrees (4:3).

For a 4:3 resolution:Change "AA" to "B4" This will give you a 90° FOV. This is a more standard 4:3 FOV.

For a 16:10 resolution:Change "AA" to "CC" This will give you a 102° FOV.

For a 15:9 resolution: Change "AA" to "D4" This will give you a 106° FOV.

For a 16:9 resolution: Change "AA" to "E3" This will give you a 113.5° FOV.