Just play it online!
You know that you can find people here and there who would say that they "finished" or "completed" the Diablo II title..
And you also know, that they do not know, what you know - this game is not about single player mode.
It is the multiplayer or, to be more precise, a massively played single player mode with individuals from all over the world killing and exping 24/7.
Diablo II is all about items: weapons, armors, shield, jewelery. But unlike other RPG games Diablo II is unforgiving for those who attempt to play the game on high difficulty levels with just basic or useless items on.
It is not about the strategy, or the cunning of one. I mean sure, at one thime or another you may get into some kind of a clash with an enemy who may force you to get some of that brain of yours working but basically it is mindnumbing fights one after another.
But a moment from now, after you have played for a couple of hours, you realize that this game just gained another dimension.
It is still about gaining experience points and it is twice as much about finding uber items but on top of that it is a faster, stronger and more intense hack and slash RPG than any other out there.
Should you have any doubts I encourage you, dear reader, to go on and ask tens of thousands of gamers out there killing Baal over and over again even after 8 years since the release date.