Advanced Dungeons and Dragons
This is one of the oldest games systems ever. And it shows. It has spawned more good ideas than anything else. But it has some issues. It can be inflexible and difficult to make any character stand out from any other of the same class. The dice rule. Or put another way, if you absolutely have to succeed at something under presure there is no way of doing it. You roll the dice and that is it. More modern games give the player a chance to succeed at everything. With a cost of course.
It has been re-invented recently with version 4.0, now call Dungeons and Dragons. This seems to have taken the game back to it's table top minatures war-game roots. Some will like this and other will hate it.
Some players like to get lots of loot (munchkins) and others play for the group. This tends to be the loot and all the loot.