I'm starting to think about longer delves in Felltower.
One of the central, fundamental decisions about my game is that you start and end in town.
We've had to violate that a few times, where it simply wasn't possible in game to leave the dungeon given the time we had in the real world to play. But that's only happen a bit less than one session in ten. Not bad given the vagaries of time to complete combats, the occasional "shortcut" that dumps the party deeper in the dungeon, and so on.
It also allows me to present "extend the session" as an option, but with a cost. I only hand out XP for delves, and a delve is defined as ending in town. Want XP for a session? End it in town. Spent two sessions in the dungeon, you get one delve's worth of XP for it. The PCs have pushed this to a three-session delve once, and ended up with nothing more than they took during day one. Not a great way to advance your character.
I don't intend to end that "start and end in town" rule. It's a good one because it allows for attendance as you wish. Players can make game-time decisions about which PC to run, which NPCs to truck along, what to do, etc. It's a good basic rule for the game.
But . . .
But my players are beginning to edge towards exploring areas that will have to take multiple sessions. Areas which may not be easy to go-and-return, go-and-return from iteratively. Some areas are absolutely take-it-or-leave-it, one-time offers. I don't want to give away too many details, but it'll be clearer when the players find them. It's fair to spend more time in them. It would be silly to make such areas and then force rapid exploration and immediate return.
On the other hand, I don't want to encourage people to willingly stay multiple sessions in the dungeon willy-nilly, figuring that they'll amortize the fixed costs of getting in the dungeon across a few sessions of delving. That might make sense in a mix of game and real-world logic. However it also means that players that missed session one of a multi-session delve have nothing to do except run an NPC (maybe.) It also means that if you're there for session one, you might have to let others run your guy and potentially get him killed off. That's not fun.
How to deal with that? I have a few rough ideas.*
GM-Forced Multisession XP
One idea is if the GM is forcing a multisession delve, then XP is per session, not per delve. However, XP award needs are based on multiple of the usual needs and awards.
For example, if you need X loot to get 4 xp, then you need 3x to get 12 xp in a forced three-session delve. Failure to meet that means you'd get 6xp. You'd need a very large swatch of territory explored to get bonus XP for exploring. Many lost NPCs and PCs would be -3, not -1, and a clean run would be 3 xp, not 1 xp.
(I could do this by session, period - award at the end, don't allow spending until town, and make a 3-part delve into a series of three individual delves . . . that seems annoying at best, and leads to complications about lost treasures, when PCs die, etc. So, no.)
So yeah, you could potentially go into an area that will require multiple sessions and come out with between 15 and 21 XP (sufficient loot, lots and lots and lots of new exploration, clean run). Of course, you could have done three individual delves and gotten those same points, too.
Almost certainly me, the GM, with some input from the players. "We want to spend just a little more time exploring this sublevel behind the one-way door" isn't going to cut it. "Sorry, guys, this room will implode one hour after you leave it, gone forever" certainly will. It wouldn't normally be for just exploring Felltower. I put in some easy ways to get around (once you get past the crust of defenses, and figure out where they are and how to use them) so this wouldn't have to happen. If you just want to extend your dungeon time because you don't want to pay the orcs another 1000 sp, that's fine, XP is still for one delve.
I say "almost certainly" because the other option is just my decision, with no input. I wouldn't hand this over to a consensus decisions because it undermines the fundamental rule. It would become, more generally, delves are as many sessions as you want them to be. I'm looking to handle special cases, so I need to have most or all of the input on what's a special case.
How many sessions?
I'll probably have to think of a par for each area that I consider like this. If I think something is a two-session-delve area, and you take three sessions, I'll award XP based on two delves.
And there are some direct complications, not just decisions to make, too.
One complication is that I have one day of real time = one day of game time (although the reverse isn't exactly true.) I'll have to decide on a case-by-case basis what that means. If a room is on Elf Hill time, that's fine, whatever time passed out of game passed in game. Otherwise, there may be forced adjustment back in town. "You left on Sunday 5/22/16, the delve was one-game-day, and you took the next seven weeks off to recover. It's now Sunday 7/10/2016."
I'm not at all sure how I'll handle players joining in. Leaving is okay - someone else runs your guy. We've done that even though it's not ideal. What happens if the players are in a multi-session delve and someone shows up?
One idea I have is to put in a new group. If Vryce, Dryst, Mo, Hasdrubel, and Gale are in a multi-session delve and then the next week Mo's player can't make it and Gale's and Hjalmarr's show up and want to play, well, we build a group around them. Vryce's player could run Gerry. Dryst's player could run Angus McSwashy. Hsdrubel's player can make up a new guy. Etc. So long as that group does a normal go-and-return session and won't overlap oddly with the other group, we're fine. We could have:
Group A goes in.
Group B goes in and comes back.
Group A continues.
Group A finishes and returns.
I could do a really weird gamey solution like, "he was following you all along" (we've done it, it works) but in some cases that won't work. "You followed us through the cursed teleporting scroll we read?" That might be a bit much sometimes. So would handing out PC summoning items (Break the stick, and a PC of your choice shows up - why wouldn't you abuse the hell out of that? It creates more problems than it solves.) GURPS Dungeon Fantasy lacks the Teleport spell for a reason, too - not just to prevent bypassing in-dungeon obstacles but also to avoid making "go back to town and get it" or "I'll just ferry us back to town with Teleport" a simple solution to most problems.
For what I'm thinking, it's unlikely there would be interaction beyond, "I'd highly recommend you don't go into that room." Unless, of course, group B is a delve meant to link up everyone for some giant combined session. Not that I want one-player, two-character situations in this campaign. Been there, done that, it was a blast, but it wasn't 250-400+ point characters.
So yeah, this is what I'm mulling over if the players do head into areas that really aren't conducive to go-and-return delving.
* None of these are final. None of this is decided. Absolutely none of this applies to our current split-session ended-in-the-dungeon session whatsoever.