Alex Schroeder writes, How's Your Campaign? And since my 3.5 game has atypical longevity, it might be worth answering.
1. How many sessions have you been playing, more or less?
About 200. Ballpark.
2. How long have you been running this campaign?
Very nearly 10 years. Our first session was in April of 2010.
3. Have you had long breaks? If so, how did you pick it up again?
We frequently have scheduling issues around the holidays and sometimes for a month in summer. Our longest breaks were probably no more than six weeks, though.
4. How many people are at the table when you play?
This has varied as people have come and gone, but we've ranged from 5-8 people at a time, myself included.
5. How many characters are in the party when you play?
Currently we have 5 primary PCs, 1 semi-retired PC and 4 followers (two animal companions, a familiar, and a paladin follower of the cleric). There's often one or two NPCs that bamf in when I remember they exist. There's a lot of history to remember.
6. How many players have you had in total over that time period, not counting guest appearances?
Eight regular players have appeared over the years.
7. Have you had guest appearances? How did it go? Did you gain regular players that way?
We've had a few. One of the current regular players started as a guest who would play whatever NPC was available, or the archmage's familiar (to great effect).
8. What have the character levels been over time?
Most of the PCs started at level 1, and they're now 19 and 20. Along the way, we had to decide what to do upon reaching level 21; as a group we decided to nix the Epic Level Handbook and just allow multiclassing and prestige classes.
9. What classes did the players pick? Did you add new classes over time?
The original group was a human wizard, human rogue, human druid, human paladin and two fighters (one human, one dwarf). The paladin died at a level before Raise Dead was available (the only permanent death) and that player returned as a half-ogre cleric of Kord until she moved away. The dwarven fighter's player retired, a human cleric and paladin of Pelor (the paladin is technically an npc follower) and gnomish bard replaced those two players. Eventually the bard's player also retired (as did the original druid's player) and an elven druid joined relatively recently. The original druid comes back occasionally.
For the most part, everybody either stayed with their original classes or took obvious prestige classes. The wizard became an archmage, the human fighter became a devoted defender (ported over from 3.0) to better protect the archmage, and the rogue recently started taking levels in Shadowdancer.
We've also had two short side campaigns related to the main one; these have allowed for novel party compositions and trials of other systems. The first was to welcome the druid back from retirement and was for two sessions; three players and myself all played druid characters from a stack of weird druid pregens. There was an alienist, a Swanmay, a weretiger lecher nudist named Hunter and the returning druid.
The second was an all-warlock party of three using the 5e rules, set in the same dungeon the main party was exploring but in an alternate universe and at a different time. It was three sessions, had accelerated character advancement (to see how 5e played) and required each PC take a different warlock specialization.
10. Tell me about some adventures you ran over that time that I might enjoy hearing about?
Ah, game stories. So easy to reminisce about with players from the game, so easy to bore third parties to tears.
I'm working on a summary of the various modules and snippets of published works I've gleaned adventures and ideas from, but until the campaign is over readers will have to be satisfied with some quick highlights (polled from my players):
- In Castle Caldwell, the party released a BBEG lich-deathknight-avatar-of-Vecna from a tomb in the basement were nearly TPK'd in the process. They got better; it was a tone-setting plot device more than a real encounter.
- The dwarf fighter developed a reputation for delivering massive critical hits from a composite bow, specifically when fighting dragons.
- The first druid had moments of pure metal awesomeness: chasing down a behir fleeing through a desert of thorns while shapeshifted into a giant eagle and calling lighting down from the heavens; leaping off a tower as a bobcat onto a gargoyle nobody could hit, knocking it to the ground and getting a grapple going; summoning a unicorn in a fight against a lesser lich only to have it impale the lich with its horn and destroy it...
- The Red Hand of Doom module delivered a few noteworthy set pieces the players remember fondly: defending the city against multiple waves of varied attackers (red dragons, an assassin, a Tiamat-blessed hobgoblin half-dragon leading a small army); fighting running battle against a super-intelligent, extremely powerful blue dragon, in the Fane of Tiamat, using the small tunnels to evade its lighting breath and spells; the half-ogre cleric of Kord, enlarged and with a stack of other buffs, killed the avatar of Tiamat (at the end of Red Hand of Doom) with a punch.
- A rematch with the BBEG some 15 levels later, in the fountain where all souls are created and sent to those being born... The human fighter, overconfident with his adamantium sword and Improved Sunder, went for the lich's magic staff, which turned out to be a nearly-fully-charged Staff of Power. It exploded, and I played the outcome by-the-book, explaining how the whole thing worked before announcing the damage (most of the PCs killed instantly) and rolling the lich's 50% chance of destruction (vs forced travel to another random plane) out in the open. The dramatic moment saw the lich survive, but he hasn't made another appearance since.
11. Have the rule changes over that time? Do you maintain a house-rules document?
This is a weird case where we're playing almost entirely rules-as-written. I did this to put as much power in the hands of the players (to make bad decisions as much as good) without relying on last-minute rules changes or favorable rulings to save them. This worked great up until about level 8; 3.5's complexity scales exponentially with level and so trying to stay on top of all of the rules instead of coming up with my own intuitive rubrics has been incredibly punishing.
If I had it to do over, I'd play by the E6 rules instead.
As for house rules, it's mainly a whitelist of published options; a ton of 3.x publications suffered from power creep. Many of the basic classes are made entirely obsolete by later classes that are as good or better than the original class in every way. Take Fighter, for example; nobody should play a Fighter if all of the splatbooks are on the table. Similarly, prestige classes are carefully selected to avoid power creep, especially when they build on already-powerful base classes (the "Tier 1 and 2"s - mostly spellcasters).
12. Has the setting changed over time?
We started in a sort of generic fantasy setting, creating just as much world as I needed to fit parts of modules I was borrowing and the big plot ideas that were developing. Over time, this grew into Greyhawk, as many modules were either from there or had good documentation about where to place them in that world.
Planar travel expanded on this; Greyhawk really only details the Prime Material Plane's surface and a little bit of the Underdark, so once the party started traveling to other planes there were whole other worlds to explore.
Regarding the footnote (adding cultures and places later, after the game's started) - the campaign has always been developed just-in-time; I'm generally not a fan of extensive worldbuilding ahead of time. I'll document some broad ideas, but all of the really interesting elements (to me, anyway) were developed during play, either as a response to players taking an interest in something (often an underdeveloped item from a published work), me having sudden inspiration, or both.
13. How much in-game distance did the party cover, how big is the area they have visited?
On Greyhawk, the party started roughly in the Yeomanry (their starting town and Castle Caldwell were retconned there), and the setting for Red Hand of Doom (the Elsir Vale, about 250 miles across) got roughly shoehorned into the southern half of the Kingdom of Keoland. Later modules would take them to Istivin, and as they became even better at rapid forms of travel (Shadow Walk and later Windwalk being favorites) went as far north as the Land of Black Ice on a whim (they needed diamonds for Resurrection spells and heard there was a dragon up there) and deep into the Dry Steppes to the west to find an ancient Baklunish ruin.
They've also been to the Underdark in several places, from a drow outpost to a svirfneblin village to a city of ghouls.
Once planar travel became an option, they've been all over:
- A trip to the Outlands to join a battle, defending Plague-Mort against demons. Or was it devils? (This was a one-shot send-off for a player and her cleric of Kord).
- A longer trip to the Outlands to find their way through Plague-Mort to Pazunia, into the Demonweb pits, and then into a tiny, frozen demiplane.
- An excursion into Elysium, specifically Pelor's Fortress of the Sun on Thalasia, to meet with Pelor and Vecna to discuss the whole avatar of Vecna problem. (Turned out it's a different Vecna's avatar...)
- A trek to Pandemonium (specifically Phlegethon and Agathion) to free an imprisoned demoted god. A short stopover at Windglum was rather entertaining.
- A trip to a demiplane of dreams, though this wasn't under their control.
- An excursion of the Positive Energy Plane (as mentioned above) to stop the avatar of Vecna from doing... something? to that fountain of souls.
Finally, the PCs have spent quite some time in the Far Realm, after following a trail of clues to Tovag Baragu, a network of portals leading to Vecna's transdimensional temple (c. mid-90s Second Edition). Most recently they've left their own universe and the Far Realm located near it, and hitched a ride with a space whale to the Outer Far Realm. Way, way, way off the map.
14. Have you used proprietary setting books? Like, could you publish your campaign or would you be in trouble if you did?
With some very heavy editing, perhaps, but it borrows very heavily from parts of so many published works it's probably not worth it.