Advice for Running a One-Shot Campaign?

[Jaguira]

I'm going to be running an epic-level Pathfinder campaign (my first one!) of my own design that's intended to basically be a one-shot, or at least very short (no more that four sessions, each session lasting no more than five hours). The gist of it is that the players arrive on a demi-plane after being swallowed whole by a colossal red dragon, and then have to find/fight their way through said plane to get to the portal leading home, which is of course protected by something huge and dangerous.

What I'd like advice on is this: how do I make this more interesting? Planar travel is neat, but players can't exactly see the landscapes their characters are traveling through, and combat can only do so much to keep the group I play with entertained. I want to make this a good campaign, so what are some ideas to stir up character interactions and interesting development, without dragging the campaign on for longer than I'd like?

Most of my players will be using characters from prior campaigns so backstories and personalities will already be fairly extensive; I guess I'm just unsure how to use them to make things fun and interesting.

[nessus]

I think you are trying to have the best of both worlds, you want them to interact and want to find ways of developing roleplaying situations but you want to do it fast. I believe that you simply cant, if you want your players to interact and roleplay but dont want it to feel superficial or rushed you need to have a longer campaign than 4 sessions. It's hard to cram stuff like that in because characters develop over time, it takes me about 3-4 games to determine what i want to with a character. Goals, interactions, friends, enemies are all things that influence role play you cant expect one to feel "real" without the other. That being said, if you still want to proceed down that path i propose you put some puzzles and riddles in there, traps and kickass treasure always livens up my games (i dont give too much kickass treasure because i have to deal with them for a while after that, but since your campaign is gonna last as long as a short video game who cares?!?) unusual characters, monsters and landscapes described in depth is good too. Try and put an npc that causes conflict and disagreements within the group (if the group naturally disagrees then you might not need one)

well thats about all i got
p.s. i would never consider dm'ing or play in a 20 hour campaign, in my opinion it streamlines the game too much you have to skip all the things that makes dnd fun. but hey, thats just me have fun :)

[Laserlight]

In terms of length, you're not doing a campaign so much as a movie; and if they've already been swallowed by the dragon and gone to the demiplane, then you're partway through the movie, at the "Can't Turn Back Now" point. Rather like starting Wizard of OZ when the house lands on the witch.

With that in mind, and thinking of four sessions:

Session 1 / End of Act 1: The party finds out where the exit is but is rebuffed by a guardian. They find a guide who will help.

Session 2 & 3: They gather items A B and C which they will need to qualify to exit

Session 4: Fight the BBEG and denoument

[Jaguira]

Great, those are all good ideas and I'll definitely consider them! Breaking down the campaign into segments especially will help me figure out where I want to go with it, especially. Thanks!