This isn't new, but when making D&D 5e one of the things the designers wanted to do was return to the core feeling a D&D game should have, stealing elements of earlier editions while also taking the game a bit more away from how dedicated to the battle grid it had become in 4th Edition. To do this, they settled on three pillars for adventure that D&D would be built around: Combat, Social Interaction, and Exploration (order may be different in the book.) Today I want to talk about these 3 things, and how they're good to keep in mind for any game, not just D&D.
I listed Combat first because it is the simplest of the three pillars to understand. Almost every table top RPG is balanced around combat and expects combat to be a regular thing that happens at the game. Even some games that try to not focus on combat, or supplant combat with some other physical activity (like John Wick's Sexcraft game) do so with mechanics that look a lot like combat mechanics just wearing a different skin.
Still, it is important to remember that combat should be fun and engaging for everyone. People shouldn't feel like this aspect of the game just leaves them out, even if they're not built to be a combat monster. It stands to reason that a character built for combat will shine brighter during combat, but that doesn't mean other people should be stuck picking lint from their navel.
Social Interaction sounds simple, but it can actually be more complex. Remember, this is a pillar that holds up 1/3 of the adventure. While there should definitely be simple and straight forward parts to it - e.g. asking the local peasants what is going on in the local castle that seems to have werewolves running around it every full moon - there should also be more to it.
Much like there are PCs and good guys built around Charisma and with stacked social skills, there should be some enemies as well. While maybe not every session or every adventure, every prolonged adventure should also have characters that need to be outmaneuvered socially. There should be challenges that are best faced through social interaction.
Above all though, you need to remember that there should be social consequences. If the PCs are dicks to the local town, the town should react accordingly. Even if that means not giving help that may be needed to properly resolve the adventure. If the PCs commit crimes, it shouldn't just lead to a combat encounter with guards but also the social ramifications of being wanted criminals in that city/area.
At the same time, there should be positive rewards for doing well. Much like how the PCs gain combat stats, gear, and bonuses as they go through the campaign they should also acquire allies and social boons and bonuses. And yes, it is possible to get both negative and positive social consequences for the same action from different NPCs and factions.
The D&D 5E PHB (Dungeons and Dragons, Fifth Edition Players Handbook...god we love acronyms!) calls it Exploration but I like to think of it as Environment. The Environment should be a factor in your adventures. There should be sights to see, nooks and crannies to explore, and all sorts of other experiences to have from the environment.
Moving further, the environment should be part of the adventure. The challenge of getting through a jungle may not be as life and death as a combat encounter (or maybe it is) but the successful completion of it can be just as vital as anything else.
Too often the environment and the area around where things are going is an after thought. But think about some of the stronger settings we have in Science Fiction and Fantasy. What would Ravenloft be if not for the intense work put into the setting and environment, making a world/area that wants to oppress you as much as anything in it. What would Dune be if not for the work Frank Herbert put into the planet Arakkis and the people and things on it?
Exploration and the Environment is not always for everyone, but having it makes the world feel more real. It will also enable you to set up more of the world and bring more tension to stories. When the players can feel the distance between two locations because you've done Exploration well, they'll also feel the tension when you tell them they have 3 days to get somewhere and they know that by normal means it's 4 days away.
Planning for the Pillars
Planning for the pillars sounds daunting when you first think about it. You have to have environmental challenges and exploration, social shenaniganry, and the usual combat. In practice though it is nowhere near as hard if you consider them in order. Look at your story and your plans and just consider: what combat encounters are likely to happen? What environmental hazards are likely to be a thing? What social interactions could be key to this story? Work them out that way, and then after you have a couple ideas for each you can weave them together.
It takes some practice, and with time you'll find you do all 3 at the same time, but it works.