So, I write adventures -- E.N. Publishing's ZEITGEIST and War of the Burning Sky adventure paths, produced by this website.
My design philosophy with adventures is that a good published adventure is a theme park. Now sure, if you have the time to plan your own vacation, you'll probably have a great time going out into the world, seeing the sights, eating at fine restaurants, and maybe having a bit of adventure. That's the homebrew game, and I homebrew myself, and I honestly prefer it to modules.
But sometimes you look at Disneyland and think, "That place has a lot of fun in one place. They've
worked to make sure that visitors have fun. I'm going to give them money and see what they came up with."
Some theme parks, and some adventures, are dinky. I played a module this past weekend which was basically just a three room dungeon with few ways to overcome problems other than by attacking them. (Seriously, there was a puzzle, and even it was solved by attacking walls to do damage with different energy types.) I don't see the point of publishing these sorts of things but, eh, it was for a 'coordinated play' series, where the bar is lower. I can forgive that.
By contrast, when I write an adventure, I'm usually doing something that will span 2 or 3 levels. I'm shooting more for 'feature film' than 'weekly 30-minute episode.' I try to check the following boxes.
- Narrow-wide-narrow design, where you assume you'll have player buy-in to "this is where we start the adventure," and you set up the antagonist to be doing something in a particular location that means the adventure will probably end up somewhere you can set up a cool climax, but the middle has a lot of routes the PCs can travel. Railroading is anathema. The players should always feel like they made the adventure.
- An antagonist whom you interact with before the climax. This has worked particularly well in ZEITGEIST, which has a heavy mystery and investigation component. It has also involved brainstorming with friends and then playtesting to make sure there's no railroading.
- An introduction that walks the GM through the most likely storyline. I present the backstory, the goals of the antagonists, and a synopsis of what events probably occur. It should always be clear to the GM what happens if the PCs don't get involved, and the GM should have a sense of what the villain's reactions are. In fact, assume the PCs cause trouble, and have interesting responses.
- NPCs with easy hooks. I've tried to give each NPC some physical trait that will stick in the players' minds, and also a personality trait.
- A 'show off' action scene, in which the PCs get to deal with people who are not a real challenge, giving the players a chance to be silly instead of brutally efficient.
- A 'puzzle combat' action scene, where the environment can be used against the enemy.
- A 'boss fight' where the boss has a goal other than just killing the PCs. Or where the PCs have a goal other than 'kill the boss.' The human brain can handle multiple threads at once, so give the players more than one lever they can pull to affect the finale.
- No 'random encounters.' These days, video games do a much better job of giving you a quick, pointless challenge that triggers an endorphin rush upon success. That's not the area where tabletop RPGs shine, so don't waste time on it. If there must be a 'traveling through this area is dangerous' encounter, have it also inform the plot or the characters somehow, or be a puzzle. God of War doesn't let you lull monsters to sleep with music, even though that's a supremely Greek thing to do.
- Denouement. In the course of the adventure the PCs should have met people who are affected by their victory (or failure). Whatever kicked off the adventure should have more consequence than "Oh, the bad guy's dead. Cool. Well, that's done." I like to include scenes where NPCs want to thank, or condemn, or offer information that will lead to the next adventure.
Now, as for designing encounters with variant party builds in mind, ultimately some of that is on the GM to tweak things to give the PCs a chance to use their cool ability to solve an otherwise hard challenge. But really, as long as you have a nice variety in threats, people will find times to shine. And since I've mostly written adventure paths, I have the benefit of being able to put material in the Player's Guide to steer PCs toward certain builds. ZEITGEIST has 9 character themes, each of which gives you a special ability, and I've mostly made sure that each adventure has one or two scenes where each of those abilities do something cool.
(Okay, the Vekeshi Mystic theme is a little under-utilized mechanically, but the plot elements tied to it are very prominent.)
The adventures I write and produce do require a lot of investment from the GM, but they offer a lot of reward. I think the GMs who post about their campaigns in the E.N. Publishing forum here are a pretty good indicator that the adventures are providing them and their players a lot of fun.
Now with that, I've got to get back to writing the final adventure. If you think making a module interesting is hard, try balancing it for 20th level PCs. Uff da. Thanks for the topic. It was nice to be prompted to consider my game design philosophy (and realize that I didn't stick to it as well as I'd like a few times).