Now that we are going to have plastic Brits soon, It seems like a good time to revive this thread a little. I hope WGA does produce some rules and I would certainly give them a try.
I personally suspect that WWI is a niche for wargaming because the common image many people have is one of hordes of men climbing over the top of a trench and charging with bayonets. Certainly every movie about the war has scenes like that. That kind of fighting did occur early in the war - especially in 1914. But for the period from 1917 on any game covering WWII can also be adapted for the Western Front in 1917-18. That is why Battlefront was able to adapt Flames of War to WWI with very few changes to the rules. For other times and places though, I don’t have much expertise but I think the fighting was very different.
If you want to do a purely skirmish level game then trench raiding began very early in the war and it occurred to me that the 0200 rules with SAS and German sentries might be adaptable for that. The earliest trench raid I have documented was by the French army in November 1914, only 3 months into the war.
Through 1915 armies on all sides were experimenting and innovating, sometimes with disastrous results, sometimes with minor success. By the middle of 1916 though, armies were beginning to learn different ways of fighting and began reorganizing infantry into platoons and sections with specialized weapons and training. For the German and French armies, the evolution of infantry tactics took place during the fighting for Verdun. For the British army it was the battle of the Somme.
By February 1917, the British army had published an entirely new manual for infantry tactics.
https://ia802708.us.archive.org/1/items/instructionsfor02offigoog/instructionsfor02offigoog.pdf
This was a revolution in infantry tactics that had incorporated the cruel lessons that had been learned during 1916. If you have served in a modern army, the platoon organization and tactics are different but definitely recognizable. I have singled out the British, but the French had already adopted a similar doctrine in 1916 and the Germans had been experimenting with what they called stormtrooper tactics since 1915. Most armies were not able to train all soldiers to the new standard - that required months of rotating divisions out of the line to retrain them. For smaller forces like Canada and Australia the retraining occurred very quickly and the BEF came to depend on them to spearhead offensives. Effective tactics did not make the fighting any easier or less costly. The periods of “open warfare” during WWI were the deadliest phases of the war by far. A quarter of all Canadian casualties were suffered during the final 100 days of the war, when very experienced soldiers were using the latest tactics and technology. From an infantry strength of roughly 50,000 men in the Canadian Corps, 45,000 were wounded or killed during that time. 25,000 conscripts helped replenish their ranks.
There are three periods of the war that I think work very well for a platoon level wargame.
The German withdrawal to the Hindenburg line in March 1917 was recently featured in the movie 1917. The first half of the film does a good job of visualizing the surprise and uncertainty the German withdrawal created. When the Anglo-French armies advanced toward the new German defenses, they did so with small scouting forces that had to overcome the pockets of German delaying forces. This was a time when most British troops were still learning the new methods of open warfare. There is plenty of scope to wargame a British or French platoon encountering a German platoon waiting in ambush in a shattered countryside. Or the Germans could be counter-attacking.
Operation Michael in March 1918 is another good period for skirmish gaming. This was the German 1918 spring offensive that they hoped would defeat the allies. They did drive deep into allied territory in many places and of course this culminated in the second battle of the Marne.
The third phase would begin on August 8 1918 with the Battle of Amiens. The following Allied counter-offensive recaptured the ground lost during Operation Michael and then broke through the Hindenburg line. Canadian and Australian forces were prominent during this phase, but British, French and American forces all began a general advance against a retreating German army.
All of those phases of the war can be played with platoon or company sized forces with or without tanks and there doesn’t need to be any trenches at all. Armies always dug in where they halted of course, but nothing like the sophisticated trenches of the Hindenburg line.