I think after so many years of having game companies focus on "High Fantasy" themes (Dragonlance, Greyhawk Wars, to name a couple), its only natural that the OSR, so far, has typically swung in the other direction, favoring darker Sword & Sorcery themes and inspirations. A quick glance at Gary's infamous Appendix N reveals that Sword & Sorcery was a far bigger influence in "the beginning" than High Fantasy, and motivationally, the game rewards
picaresque edpisodes far more often than grand quests anyways.
But that's not to say that High Fantasy gaming is without merit. Far from it. Enough folks enjoy the genre that I suspect its only a matter of time before the OSR starts to produce some cool material to specifically support High Fantasy themes oo.
In the meantime, here's a quick and dirty method to develop your own High Fantasy campaign:
Episode 1: Red Dawn. In this adventure, the PCs are generated, and are considered to be relatively naive villagers going about largely peaceful lives. Then the forces of the "dark lord" appear and the party must band together to help defend their homes in a running set-piece battle. Whether successful or not, something must be done about this villain!
Episode 2: We're off to see the Wizard. This would be a short wilderness adventure, wherein the PCs get to see firsthand the deprivations the dark tyrant's forces are inflicting upon the lands, on their way to consult the wise loremaster.
Episode 3: I wonder if he means old Ben Kenobi? The PCs meet with the wise loremaster, the Elrond of the campaign setting, who fills them in on the dark lord's history, the obligatory prophecy of his fall, and where to find the great artifact that will enable his downfall.
Episode 4: Excalibur! In this adventure, the party must travel to the campaign setting's premier dungeon, and plumb its depths to recover the great artifact.
Episode 5: One does not simply walk into Mordor. In this wilderness adventure, the party must venture into the lands of the dark one, hounded at every step by his most powerful servants, who by now should be aware that the powerful artifact is in the party's hands.
Episode 6: Nottingham Castle. Not wanting to deal with the huge evil army camped out in front of the dark lord's abode, the PCs must win their way in through duplicity or through a back door. The basements and sewers of the dark tower may be a dungeon adventure in their own right.
Episode 7: There can be only one! The final part of the campaign, a magnificent set-piece combat wherein the PCs at last face their nemesis and his most trusted guardians. Will they save the realm, or doom it?
There you have it, seven easy steps. Two set-piece battles, two dungeons, two wilderness adventures, and some cool "show off my campaign world's history" exposition thrown in for good measure. Some DMs might enjoy letting the characters level up after every episode, rather than tracking experience the traditional way, a method perhaps justified by the narrative they are participating in.
Keeping the episodes as fast, open-ended, and loose as possible will go a long way towards avoiding too much of a rail-roady feel, as well as letting the players know up front what sort of a campaign they're in for. Avoid planning
too many details in advance, and you can even enjoy a bit of the shared worldbuilding so well facillitated by sandbox play. Also, if the party's quest is successful, you might get to enjoy another neglected element of D&D, the "endgame" where they set up their own baronies to help rebuild their shattered homelands.
