Great Battles of WWII: Stalingrad is probably my most played RTS, that fact the scenarios are as historically accurate as possible makes in interesting to a history buff like me. Plus, each mission offers literally hours and hours of gameplay. My most recently completed mission in it took me 27 save games to finish.
Definitely the best game based on the Blitzkrieg engine in my opinion.
Definitely the best game based on the Blitzkrieg engine in my opinion.