Sandhurst chaplain Paul Wright has updated Wells's rules - retitled Funny Little Wars, external - and says about 100 people in the UK still play it. A veteran of Iraq and Afghanistan, Wright has been war gaming since he was a child.
"As an army chaplain, having buried a lot of people and had friends of mine killed, I'd hate to think I was trivialising war but I don't think I am," he says.
For a lot of people, says Brian Carrick, one of the Union "generals" at the Sandhurst recreation, the fun of war gaming is "about the rules and recreating history and experiencing command in a battle - but for me it's simply about playing with my soldiers. I collect them, I paint them, I enjoy them and this gives me something to do with them."
The actual firing of miniature artillery pieces is at the heart of the Wells school of war gaming.
A Funny Little Wars game sees rival commanders bombard their adversaries with matchsticks, fired with little spring-loaded triggers in the tiny cannons. Careful measurements from where the matches land decide the number of victims.
This is looked on with disapproval by some modern war gamers, who prefer theoretical bombardments worked out with distance tables.
Phil Barker, a celebrated deviser of modern games, acknowledges Wells's role in "showing it could be done - and giving grown men an excuse to play with toy soldiers".
But he adds: "Combat was based on shooting solid projectiles at the figures. Today, this would be discouraged because of the risk of someone getting a projectile in the eye, but it was the chance of damage to the finish of lovingly home-painted figures that led to the switch to less lethal dice."
Wells's rules and Padre Wright's update are praised by knowledgeable wargamers for their simplicity, but to an an outsider they are complicated enough.
Wells laid down that a gun is captured "when there is no man of its own side within six inches of it", and at least four opponents have "passed its wheel axis going in the direction of their attack".
There are rules about how much forage the cavalry need every six moves and how many moves it takes engineers to rebuild a railway bridge.
At Sandhurst, the early stages of the battle bring success for the Confederates. The Yankee side deployed a lot of men to receive an expected attack from the west.
But when they get close, the Confederate flags on that side turn out to be dummies, and the blues are left underprepared for a mass grey assault from further north.
For Wells, the horror of WWI and what he called the "almost inconceivable silliness" of the top brass had a great effect on him.
"Up to 1914 I found a lively interest in playing a war game, with toy soldiers and guns... and I have given its primary rules in a small book," he recalled.
"I like to think I grew up out of that stage somewhen between 1916 and 1920 and began to think about war as a responsible adult should."
That makes it sound as though Wells cashiered his toy soldiers. But he did not.
The writer Colin Middleton Murry later recalled a war game on a childhood visit to Wells in the 1930s:
"He rushed round frantically, winding up clockwork trains, constructing bridges and fortifications, firing pencils out of toy cannons. It was all quite hysterical - quite unlike any grown-up behaviour I had ever known."
War gaming is fun but is also a pointer to the true horror of war, Wright says. He agrees with Wells, who wrote of his game: "How much better is this amiable miniature than the Real Thing!"
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