In essence, Hearts Of Iron II is to WWII gaming what Championship Manager is to soccer, in that it's as much about lengthy preparation and intricate resource management as it is to taking to the field and hacking down your opponent. This should give you a good idea of what's in store should you choose to purchase what is probably the best global-level strategy game ever devised.
The manual for Hearts Of Iron II is such a size, but even when you've waded through this tome, the author actually stresses that his guide is a mere introduction, rather than an exhaustive point of referral.
When a game comes with a instruction booklet, you know you're getting something with some degree of depth.