As another commenter mentioned, using the Havoc Engine objective system to represent the fog of war is a sharp choice and helps sell the grittier, more grounded fiction you're gunning for here compared to Eat the Reich. I think your other mechanical choices support that fiction well, with the lethality die slowing the crawl towards each objective being a standout choice towards achieving the senseless hostility and slogging pace of trench warfare.
The visual design choices definitely help sell the fiction, but I found large blocks of typewriter text a little difficult to read at times. I'm definitely interested to see the VTT stuff you've set up when the links are ready to fire!