The method we're going to use is hex editing the 640x480 value in the game's executable to a custom resolution of our choice.

Firstly, you'll need to download and install a hex editor such as HxD[mh-nexus.de].

Navigate to your game directory by right clicking the game in your library and clicking properties, then under the local files tab, clicking browse. You should see a file called "dusk.exe". Open this with your hex editor.

Navigate to offset B9889 (ctrl + G in HxD):


The value highlighted in the following screenshot represents "640":

This is an IEEE float value represented as hex. To replace this with your desired width, we will need to do a conversion.

Navigate to https://gregstoll.com/~gregstoll/floattohex/ and type in your desired width in the float value box, e.g. "1920", then click "Convert to hex". Ensure swap endianness is checked.

Now insert the new width value in place of the old one:

and repeat with the height value, which starts at offset B9893:

Now save and run config.exe, then select 640x480 as the resolution.

and the game will run in your new custom resolution.