Hearts of Iron

In the game you take the role of the ruler of either the USA, Germany, or USSR (Comintern). Each faction has its own benefits. The Germans are all about their heavy tanks (tougher to kill) and killing other units outright but also have the most expensive units to build. The USA is all about artillery and airpower but have lousy tanks and poor organization and leadership. The Russians are all about throwing waves of cheap infantry as cannon fodder at the enemy (think Enemy At The Gates) but have lousy airpower.