I made the decision early on that I wanted units to be company sized. Companies are where the difference in unit types show up. A battalion is not actually a homogeneous unit, an Infantry battalion, for example, may contain a heavy weapons company, an anti-tank company and even an attached engineer company.
On the other hand weapon ranges are quite long. A typical WWII rifle can shoot 500m with accuracy and can deliver fire up to about 3km. Artillery ranges for howitzers are measured in kilometres and naval gun fire can be delivered on target at ranges of 30km or more! A division can have a 15 to 20km frontage. With a scale of 500m to the hex most battles will cover a lot of screen.
Board games of this period did not offer much in the way of mechanics ideas so I looked at miniatures. After a fair bit of study I realised that I would need to separate out fire combat from close combat. This worked out well once I included the air power operations for attacking ground targets and interdicting movement and supply.
Also the line of sight thing has been interesting. With 50m contours on the ground and various obstructing terrain and weather conditions it becomes an important factor. Where did those Panzers go in the fog? Can my forward observers call down an artillery barrage?
Then there was chain of command, dealing with radios, laid cable, runners, and the need for good communications in order to get supply. The more this part of the system began to be developed the more important road networks became. At that point I realised I needed to add in cratering effects from bombing and artillery. So now it is possible to lay down a barrage on a key crossroad just to reduce its usefulness for communication and supply. The same goes for bridges, with engineers blowing and building bridges for reasons other than simple troop movement.
Needless to say this is all quite complex for the player so there is a lot more work to do on giving players adequate feedback on what's happening. Also easier methods of giving general commands to battalions and regiments.
On top of all this, there is the scenario editor. Probably a bigger project than the game itself we want to allow our players to research and develop scenarios themselves. Our rough and tumble internal editor, which relied on us knowing how to tweak XML, will not do!
That's all for now. I'll keep you up to date as things progress.