Might & Magic is a series that's fallen into disuse lately, which is a great shame because, in many ways, it is the most faithful homage to the old-style, exploring-for-its-own-sake D&D campaign ever sold as a computer game.
First off, it is highly non-linear. Each game's dozens -- maybe even hundreds -- of quests and tasks tend to be scattered around the world in a semi-scrambled fashion. Players are left to their own devices as far as figuring out what to do and what level they should be at to do it.
I must remind the reader that this is a style of game that relies on the use of unlimited game reloading, so players can recover when they unpreparedly run into that group of Cuisinarts while less than level 200. Usually the player has no clue an area is out of depth for him until the monsters wipe him out.
Once granted this quirk, the M&M games are marvelously open-ended and wondrous experiences. They remain one of the few games to adequately express one of the most unique joys of the old-school RPG experience: that of unabashed powergaming. Might & Magic II has a magic space in one of its caverns that grants all the characters, one time only, a thousand free max HP.