To get the game working in widescreen, you'll want to do the following:

1. Download the widescreen fix from the link below:
https://www.dropbox.com/s/xwt0jgq0i0ji6lz/HC%20widescreen%20fix.zip?dl=1

2. Unzip and paste the files from the file you downloaded, into your game's main folder (C:\Program Files (x86)\Steam\steamapps\common\Hitman Contracts\). You won't need to overwrite any existing files.

3. Now go to: C:\Program Files\Steam\SteamApps\common\Hitman Contracts\

4. In there, open the "h3.ini" file that you just pasted and change "Width = 1280" and "Height = 720" to reflect your current desktop's resolution values. For example, since my desktop resolution is 1920 x 1080, my "h3.ini" file would like this:
Width = 1920
Height = 1080

And that's all there is to it. Everything should be fine but if your map is frozen in-game, you might need to do an additional step:

5. Open the "HitmanContracts.ini" file (found in C:\Program Files\Steam\SteamApps\common\Hitman Contracts\) and add "Window 1" (without quotation marks) to the bottom of the file and "StartUpperPos 0,0" (again without quotation marks) below that Window 1 line. Now just save the file and try launching the game again.


While there is also a letterbox option in the "h3.ini" file ("Letterbox = 0"), changing 0 to 1 personally didn't do anything for me.