The Hexwar.com online game playing service provides a very user-friendly way to play some classic SPI/Decicion Games titles. Every game can be played just as the printed rules specified, which many players prefer.
But quite a few of the games also offer a "Fog of War" option, which causes units located a certain distance away from any enemy units to be invisible to the enemy player.
In many games this has a minor effect. There's not too much scope for hidden movement to effect things in Cemetery Hill, for example.
But sometimes the FOW option can really change the entire nature of the game. One game where this is true is Arnhem, and I believe the Fog of War option is largely responsible for the noticeable German bias for the game. According the Hexwar.com's statistics as of Jan. 27, the Germans have been victorious 3,703 times compared to 2,788 Allied wins.
Now, the Market Garden situation is inherently challenging for the Allies. They did fail in the historical battle and most games on the topic reflect the challenges the Allies faced. But of all the games on the topic, the basic quad game version of Arnhem seems fairly friendly to their cause. The German forces are very badly outnumbered and the map is depicted in such a way that the Allies' critical supply road has a wide buffer zone around it. In comparison, Target Arnhem puts the road within striking distance of flank attackers throughout most of its length.
The total German force totals 61 attack factors of 7-move infantry, 27 attack factors of 10-move armor/mech units, 6 attack factors of 12-move recon and 13 bombardment factors of artillery for a total of 107 factors. The Allied army comprises 68 factors of airborne infantry, 12 factors of airborne artillery, 26 factors of regular infantry, 16 attack factors of armor, 3 factors of engineers and 24 bombardment factors of artillery, for a total of 149 factors. On some turns the Allies also get up to 7 factors of air support.
While both armies suffer somewhat from piecemeal arrival and geographic dispersal, the Germans have it worse because the river lines and presence of Allied forces will prevent them from massing their troops, while the Allies benefit from interior lines. It;s fairly easy for the Allies to mass against the Germans, given prudent play.
The Fog of War option changes this all this. Now it's the Germans who can mass. Unable to be sure where the Germans might be coming from the Allies must spread out to guard the supply road, whereas the Germans can mass their troops to try to cut the road. There's a very big payoff in victory points for cutting the road and doing it a couple of times will probably be enough to win the game for the Germans unless the Allies manage to break through all the way to Arnhem in strength.
Hexwar.com statistics don't break down the Arnhem results between classic and FOW-style play, but based on my experience I think the vast majority of games are played with FOW.
It's an interesting way to play and highly recommended. Despite the imbalance, playing with Fog of War does seem much more authentic for this particular scenario.