In view the time of year and the possibilities of that “Christmas Dungeon” I thought I'd share some stuff I learned in a previous life. Also, have you considered running that Christmas dungeon all year round?

A long, long time ago in a far fat distant land I finished GM-ing a longish campaign of Ye Olde Runequest and our group discussed which game I should move over to. There were four of us and we GM-ed different games for each other in rotation. I seem to recall we had games of Bushido, Aftermath! and something else running at the time? We had all begun on ol' Gygax's AD&D and had had some fun being vaguely bizarre with it. I think we were feeling vaguely nostalgic for the simplistic innocence of the game system and its vast array of silly renaissance pole arms. As a result I agreed to run a short AD&D revisit campaign and decided on a high rewards environment to speed up character development - but most of all we wanted it to be silly.

It's not easy to make a humorous campaign but I think we had all just read Terry Pratchett's "The Colour of Magic" around that time - so I guess that dates all this to the early '80s. Oh dear!
Anyway – parody books are an obvious and good basis for inspiration even though at the same time can be an obstruction ("Oh I can't do that! It's too 'Pratchetty', they've all read it. Hrm.") So, in a nutshell, whilst it would be fun to generate a character sheet for The Luggage, it's a joke that has already been "done". That's what makes humorous GMing so painful - you have to try to be original – particularly about specifics.

That presents me with a problem here because, writing this, I can't say "Use this" or "Add one of these" or shove too many examples under your nose - in case your prospective players read this too! Arrgh.

So it's going to have to be "pointers" I'm afraid. I'm also going to be primarily considering Fantasy Gaming here - it's easier to make fun in a magical realm than an Earth based Post Apocalypse campaign. Now there's an idea! Millions of dead, devastation all around, good soil for growing humour. Er...

I should also explain that as a GM I tend to be one of those who likes visuals, handouts and surrounding details. It's labour intensive but I enjoy  making maps and thinking up characters for places the players may never even visit - but they might!

However – Main  Rule!!! It doesn't have to be "funny ha ha", that's next to impossible. Downgrade your expectations to "Silly" - that we can all manage. The point here is that the environment sets the standard for the players to fit into.

So...

The Universe
I started with a viewpoint of being "God" - I am creating this world and I'm creating it because I, as "God", want to experiment with life. I am whimsical, I can create what I desire with no recourse to Science or Causality - those are minor gods who have to bend to my will. The Universe is my plaything. I can make the worlds flat or spherical or any shape I please. The players may never discover the nature of this aspect of their world, but it helps shape creation thereafter.
I didn't make it flat, exactly. I made it a giant Polo [TM] mint (for U.S. Readers this is a mint Lifesaver) - toroidal-ish with raised printing on it. The sun rose in the centre of the toroid and set around the outside. The sun precessed around the toroid making seasons. You can work out what it would look like from the perspective of life on that sort of world. Navigationally, of course, the sun always rises in the same place, which is useful.
The land lay on the raised portions of the printing "POLO", each letter a continent in itself. I could now make my continental map of "P" - the players all lived on this. It was heavily eroded by the seas.

Debris from space had coated the world as soil so it is only by mining extremely deeply could one ever hit pure mint! This should obviously be a Dwarfish High Secret (stash that idea away).
As we can see, the players may never learn these ultimate secrets but they set the GM mind in the right frame from the start.

Now maps!
I love maps. I can study them for hours both for their artistic merit and factual content. Living in the UK one can often muse over the strange names we have for places. Yes, even Brits are amused by our "Six Mile Bottom", "Bishop's Itchingham", "Great Cockup" or "Lord Hereford's Knob" and so on. Most countries have them especially given our language barriers. Try looking for "F***ing, Austria" on Google maps.

So I went mad on silly names. Some of them were relevant to the players, like the companies they worked for. Ah! Must have been around 1984! I think that's about when we started work proper.
I worked for GEC Avionics. Easy - a sea - "The Jeeyee Sea". Done. Similarly Plessey but that needed fiddling - "The Pearlessy Sea". IBM? Trickier - so a country called “Eyebiem”. They're not "funny ha ha" but they're not difficult to make up.

You'll have deserts, mounts, flats, lakes and so forth to play with. Keep a note pad handy wherever you go and when you're waiting for the bus try to think up just names for things and jot them down... it's often easier than thinking up serious names - clichés are to be desired rather than avoided!

So the same for NPCs!
I think I had people named after various commodities - there was a "J'Fa the Orange" - a dragon of some sort, I think. No, not inspired by the character in Disney's Aladdin.
Sure, pinch some ideas from literature. Pratchett has a rickety old hero called Cohen the Barbarian - I see no reason why every game world can't have a Cohen. Or his antithesis, lots of puny little jerks called Conan everywhere - all named due to a hero celebrity culture.
Besides names, design NPCs with quirks or often predictable responses – AD&D Lawful Evil people might obey almost any “reasonable” seeming command – to them. In a different game, we had a Paladin, who, through killing the Evil original owner wore significantly magical plate armour. It was black and being magical “glowed black”. What is your LE NPC going to think when faced with such a senior looking personage? Try to factor in weirdness. Your NPCs could be confused, emphatic, distracted, sycophantic, obsessive, anything, but don't try to be too “clever”. It might be fun as a GM to have convoluted characters and plots but they don't really work in this sort of game.

Think about towns and think of the details.
Don't fall into the traditional “Magic Shop to sell stuff, Tavern to sleep in, clues to the next dungeon” format (as if you would!). Or DO!!! but turn it around or configure it unexpectedly.
Useful concepts to adjust your world are aspects of our modern world - franchises, speciality shops, malls. Think about weird services that might be available for transport, information exchange, storage, repairs --- sex! I seem to recall one early adventure I created was a raid on a local Olde Sexxe Shoppe. I'll leave the reader to imagine possibilities here.

In previous games we had already established vaguely cynical "short cuts" to "standard features" like ROTD (Rumour of the Day) and TWOTS (The Word on the Street) - chuck those in too.“Getyer twots 'ere!! Buy two an' get one free!!!”. It's not so far from reality anyway.
Food and Drink concepts - forget drug pushers! - what effects are you likely to get from the local brew - "Old Grumbling's Mushroom Beer"? Is that actually a sausage for a straw?
The real world has been inflicted with all sorts of stupid laws through history - as a Brit I find it odd that US states have differing rules - what if every village has its own subset and stuffy little militiamen to lock you up for "Inappropriate Use of the word 'Fecund'"?

Gods and religion? Don't even get me started. We've got three major religions who all agree they worship the same God and so they fight over which prophet is right. Babylon 5 had the Drazi fighting over “Green” or “Purple”. If you can't throw silliness into a game with this sort of thing then - well...

Then there are the dungeons.
In a serious game you can be at a loss for reasoning why and how one exists or you just chuck the economics into the Gygax bucket. Who cares that to create a dungeon should cost millions of gold pieces? Who feeds the monsters? What are the logistics for delivery of essential goods? Bah!
Are you the kind of GM that plans in the toilets for the guards or gives them somewhere to wash their smalls?  Do so. Every sordid little detail can be fun to explore.

In our original D&D campaign we players already established the existence of the "DMC" - the Dungeon Maintenance Crew. Sometimes there were signs at junctions saying "Dungeon under Construction - No Entry" so we knew not to go there yet.  Throw that into the mix. I dunno, have an indestructible harmless tiny gnome with a shovel wandering around who explains "ME? Huh! I jus' shovel the sh*t." and grumbles about the pay and the dental plan.

In a magical world without limitations of "economics" you have an infinite variety of possibilities and clichés to exploit. The most convoluted and pointless traps and secrets are yours to peddle.
A final word about "dungeons". Your players just "cleaned out" a castle infested with all the uglies of monsterhood you could infest it with. Who owns it now?

Player Characters...
To some extent I found that "engineering" the team is usually useful - but by no means essential. You should ensure a decent variety of skills to maximise exploitation of available clichés. At least make sure that the essentials are covered.

I've often found that my own characters in “serious” games are not really as "heroic" as I'd like. Playing mostly GURPS these days, where the character's active "heroic-ness" is essentially defined by his number of points - and where many of those are buried in skills not often used - the character starts to become more humdrum and much like the NPCs he meets. Sure, he's a great shot with a gun and has 2 points of reputation for saving so-and-so but... hardly "heroic". Couple that with the inflationary nature of the enemies you meet (to keep the "challenge alive") and you start to feel very ordinary. Now add some GMs' preference to add "Illumination" into the mix - those wretched "untouchable enemies" who are always one step ahead of you and... oh hell do I feel small and useless!

Make your players feel heroic when they are! There are all sorts of added annoyances you can inflict on them due to their fame instead! Puny little "Conans" who want to prove themselves against them, monsters that run away and then throw dung at them from a distance? Monsters have feelings too!

Inflationary enemies? Not always. Occasionally throw a horde of Level 1 goblins at your five Level 20 PCs, they can enjoy scything their way through useless enemies and then try to work out how to sell 100 not-very-good assorted weapons and armour. How to transport it all? Is it worth it?
Let the players be "Bourne" in his Ultimatum if they want - but not all the time.
Sure, they can save the world before breakfast... again... but it doesn't mean that the local Town Crier hasn't got "the scoop" about one of the PC's sexual proclivities - true or not.
OK, have “illuminated” elements, just think “what if” they're a bit crap at it. Their operatives don't expect to be attacked so perhaps their armour is just for show and effect – due to cutbacks?

Treasure.
Be generous. Silly money makes for silly games. My guys were so loaded it cut out all the humdrum tedium of "Oh, look! A slightly better sword than the one I have, now if I just had 10 more SP's..." They could afford henchmen with "golf bags" of weapons if they wanted.
"Ah, now then, for this monster I'd recommend the Number 7 Bastard Sword, sorr!" *Touches forelock*.

In reality, in the campaign I created, the lucrative nature of the game sometimes meant a lot less work for me than I imagined. My players started to become "businessmen" - they started a chain of nightclubs (a new concept for the world they were in) - and spent wads of cash making "themes" for each one. I remember them needing to do a set of job interviews for the manager of the first branch. They started playing between themselves, discussing and creating what they wanted and all I needed to do was sit there and "yea" or "nay" the concepts, tell them costs, difficulties and other needs. I had a brand new dungeon all ready to be played and we started it several hours late. They were enjoying themselves and that was what was important. Dead easy for me.

Remembering, of course, that not all their ideas will work! They had an idea for a forest themed nightclub and got an architect to design a mansion for it. My NPC advisers suggested it was the wrong idea, their customer base was likely to be the Rich and they all lived in mansions already! What was needed was something like an Elven theme world, treetop houses and walkways and silly food and so on. Stuff that their rich clientèle did not have experience of. They weren't having it and had the game gone on further that venture would have flopped... badly.

As mentioned above - who owns that cleaned out dungeon? Can you sell it to a new proto-evil world dominator? Maybe they could interview the potential new owners? "So? How much of the world do you expect to be 'Evil Overlord of ', after, say, five years?"

When I started to write this I thought it would be short and I was wrong. My apologies. A lot of this is obvious and might be useful as a reminder for your Christmas Dungeon. For a campaign just think of  the “Director's Cut” of that. Your game should be like a simple breath of fresh air after the smog of more complex campaigns. Sometimes it's fun just to “let go” for  a change.

Which brings me to a final point.
Work from the presumption that the campaign will not be a long one and make sure that the players know that when the first one of them is starting to get bored with it (or you are) then it'll stop. Then file it away and bring it out again at Christmas, perhaps? It's better to end on a high.

Now get the old cliché grinder out!