This is also a nice strategic turn-based game running under DOS. You can even download it for free, it's only about 7 MB.
I tried to find out the longest path of the '39 campaign.
This is the .gif -file version of the longest path.
This is the MS Project version of the path.
This is also a description of the campaign flow.
This is a very nice guide for the game I found on the net.
Panzer General @ www.ezboard.com
Panzer General & Allied General Page
Panzerfather`s Panzer General Homepage
This is also a great game. The same game mechanism like PG, but with nice images, landscapes. There are plenty of custom campaigns, scenarios, e-files, etc on the internet. The forum and link below are the best starting points, if you want to find more resources.
The Praetorians Oasis - Main PGII Talk
Pacific General and PG II Armory
Again, the same type of game, but not about WWII, but WWIII ! Tanks with 3 range, artillery with 10 range, etc.