I gave up because putting the roundels all over the map and numbering everything got very tedious.
Combat would be limited to 3 rounds, and after that you can retreat or your can dig in, but this exposes you to counter attack.
Tanks (and mech when paired) would have some cool rules.
First of all, they can roll to retreat as the defender after one round of combat. (you may only retreat half)
Second, they could blitz into new combats.
Because combats last 3 rounds, for mechs and tanks, if they participate in a combat that ends in the first or second round, they can blitz into another combat and fight for the remaining rounds. In this way Germany can really pour into Russia and France.
Not sure 100% what the city circles would do, but in the very least they would allow defending infantry to defend at 3 during the first round of combat. (representing how difficult it would be to take a city)
For movement, something like “city to city” might be possible.
For instance, the IPC values of each city is how many units can use its rails to ride to any other city within 4 spaces (noncombat only)