Yeah for some reason 688(I) works fine in my Windows 10 with no Dxwnd or .dll fixes or anything, unlike Dangerous waters, go figure.
If you have an Nvidia graphics card, you can change this setting in the Nvidia control panel. Start up the Nvidia Control Panel, go to "Adjust desktop size and position" under the "Display" category, and under "2.", change the scaling to "Aspect ratio". For me, this was not enough, as I had to change the option "Perform scaling on" from "Display" to "GPU". There is a little preview window that should show black bars on the side if it's scaling the aspect ratio properly. Just tested this out and 688(I) now runs in 4:3 for me with black bars on the side
If you have AMD/ATi, this process will be similar but you'll have to look it up on Google as I don't have AMD/ATi to describe the steps.