I tend to find Marvel scenarios fairly easy to make-up, and generally don't use more than a couple of pieces of loose-leaf in making a session or two worth of play for a single player game.
Now, the last longterm DnD campaign I DMed, that was a different story ... with all of the locals that had to be detailed, the dungeons and mazes and room details.
It was a doozy of a campaign too; set in a customized version of Forgotten Realms and revolving around the fulfillment of one of the prophecies of Maglas ... "Anf dragons shall rule the world entire." I defined Sammaster the Mad (founder of the Cult of Dragons) as the offspring and lover of Tiamat, birthed long ago to herald a return to the Age of Dragons with Tiamat as that ages Absolute Monarch.
What a campaign! By the time the bottom fell out, Sammaster had been resurrected, Tiamat gated in the world, Cormyr was in shambles and fracture in two, its was King dead, the Darkhold had fallen, along with the entire Sunset Vale (awash with undead that poured out of the Battle of the Bones), and the forces of man were scrambling to do ... something, anything to halt Tiamat's army of dragons.
As a last ditch effort 5 adventuring parties were sent out to find either the Orb or the OrbS of Dragonkind, spoken of in a legend so old that even the elves were unsure of its authenticity.
The PCs made up one fo those parties, but had many adventures prior ... Especially Hector the Mage. He blew which ever way the wind blew ... starting as a wide-eyed mage from backcountry Cormyr, then being seduced by the Cult of Tiamat with the lures of money, power, and women, sacrficing children to learn long forgotten secrets, then betraying Tiamat to an even more ancient evil when trapped alone in a desolate ruin in a foreign land far from home, selling his soul ot that ancient evil in exchange for survival and power, then betraying that evil and returning to the cult of Tiamat, betraying his adventuring band while exploring an old prison ruin called the House of Toil and Sweat, then betraying the Cult of Tiamat following a near death experience (in which he saw the ancient-er evil) and becoming a servant of the god of renewal and vowing to undo all the evil he'd wrought ... including giving the cult the power to ressurrect Sammaster and gate in Tiamat!!!!!!
Hey, hold on here. This is a comicbook list right ... superhero comicbooks ... 'nuff said. :D