I took (what I thought was) a big risk with my campaign. Dn. Goram was Geased to find and return the Two Swords to the Lost Temple underneath the Monastery of St. Urheim. Ahkmed the Dwarf has a map to some kind of dwarven treasure/lost colony (actually a slightly modified version Mr. Raggi's Hammers of the God). I had also recently bought Realms of Crawling Chaos and was eager to integrate ideas from it into my campaign. As a result, I decided to give Dn. Goram a clue to lead him in the direction of the Dwarves (who live in a mountain range to the southwest of Headwaters) and happily placed elements from RCC and Hammer of the God in the area. The risk: the Two Swords had been placed into another dimension by some monastic dwarves in order to protect them. That other dimension happened to be a spaceship.
Thus, the dwarven monastery occupied by white apes and their minions was full of RCC-derived stuff and sat upon the mountain where I placed Hammers of the God. The party succeeded in clearing out the dwarven monastery of its ape-like occupants, fended off an attack by some harpies and their slaves and proceeded to manufacture the formulae that would allow them to dimension hop. This required some uncomfortable ingredients — some of which they were able to find in the monastery, others they had to procure.
After quaffing the first dose of the formulae, the party found themselves in a spaceship (though it took awhile for them to realize this, given my method of trying to describe things like plastic and computer screens). When it dawned on my players what I was doing, one gleefully exclaimed "We're playing a little Gamma World today!" Despite my trepidations for so blatantly breaking genre, my players had a terrific time. They encountered a number of slime-like creatures with a variety of special abilities and immunities (and proved to be quite a challenge for the party). The party was quite shocked when one such creature swallowed Dn. Goram whole. Fortunately for him, the four-hour-dimension-hop ended before he was digested.
The exploration of the ship required three separate trips. They found a variety of tools and food-stuff that was the equivalent of treasure as well as the remains of the crew that apparently died some time ago in a mysterious manner. In addition, they found a type of prison where a number of strange creatures were being held in stasis (including a shocking number of mind flayers). They found what they believe to be the Two Swords and managed to retrieve them both, but not before messing around with the ship's nuclear reactor. Their actions caused a meltdown which was going to destroy the ship and everyone on it. Fortunately, the party was prepared and cast a Dispel Magic to pull them back into their own dimension before the whole ship went boom.
These three sessions ended up being some of the most rewarding I've had during this whole campaign. It combined some of the things I like best about old-school play: exploration driving plot, deadly combat, genre bending locales and player freedom and creativity. My players really enjoyed themselves and wanted to know more about the mystery of the ship and what it was all about.
As a result, they decided to find the dwarves and report to them what they found. In process, they discovered that the Dwarves blame one of their own for the fall of the Thassalonian Colonies, of which the appearance of the Golden Masks was a consequence. They warned the party against pursuing Ahkmed's map (much to my own disappointment). The party did some trading and began to establish some economic ties to the Dwarves (who were extremely interested in some of the technology the party brought back with them from the ship).
Finally, Ahkmed found out he is now what the dwarven loremasters call a Bane-Bearer. His sword Hornet was forged along with several other weapons. Each is a bane of a specific race. They were created in an attempt to keep peace between the various races; however, an evil dwarf managed to collect them all and wreck havoc upon the races. Since his defeat, these Bane-Weapons had been lost — until now.
One final note: when I began doing these session reports, one of the things I was interested in observing was how a bunch of players who came into the hobby with 3.5 would react to old-school rules and play. After 35 sessions I can now report that all of the guys in my group have officially dropped 3.5 in favor of a variety of older rulesets (primarily AD&D and LL). Interestingly, one of them has gone out of his way to buy a bunch of Judges Guild stuff (having been introduced to their existence through my campaign). As he was excitedly reporting to me some of his finds, he exclaimed, "The old stuff is so much better than the new stuff!" To riff off ye auld bard, the play is the thing.