I've run and played in a lot of games as you can tell by looking through my blog posts. Those are only my convention games and they don't include my regular weekly games.
So, what makes a Great Game Session?
Great games for me were games that flowed well, that was fun and exciting, and the players brought their brand of crazy to the table that made everything memorable, games that I remember fondly many years later.
I've discussed this with Shannon M. and we came to the conclusion that it was a combination of 50% GM and 50% Players. A great GM could have bad players and bring the game down a notch. A bad GM could have great players bring the game up a notch or even save a horrible game.
So a great gaming session is a combination of a great GM with great Players at the table.
What makes a Great GM?
Preparation
The GM needs to know the rules. Or enough to fake it, but if you fake it and have a player that's a rules lawyer, it'll kill the table. Ezra D. won the title of
Big Bad GM one year and he was vaguely familiar with Fate, the system used in the contest. Luckily, no players rules lawyered him.
The GM needs to know his or her scenario. You don't have to memorize everything, but you need to know the flow and why things are where they are. If you do, then you can move things around on the fly and not interrupt the flow. If things are going wrong, you can always call for a break. And while everyone else is going to the bathroom or getting a snack, you can go over your notes and figure out what to do.
If you don't have a good memory, then a short one page outline that you can reference would be very useful. You can also use different colored highlighters to color code various things (an old college note taking trick).
Flexibility to say, "Yes," and Improvise
If you understand your scenario, you would understand what would break it and how to weave changes into it. A game is a collaborative process. If the GM is the producer of a play providing the scenery (world system. e.g. 1920's CoC), the set (smoke filled speakeasy), the lighting (gritty and non-pulpy), the spear carriers (NPCs, bar employees and drunks), and the conflict (the drama and instigating action. e.g. a nun gets chased into the group of PCs by cultists), the Players are the improv actors providing the dialog and action and emotional content.
So, if a Player wants to do something that's reasonable, within the PCs abilities and doesn't break the world's rules, I'd let the PC try the action even if it was totally out of the box (unexpected, not covered by the scenario if a published scenario or you if you wrote the scenario). It is up to the GM to provide the target numbers and to determine the side-effect of failure. If the action is interesting enough, the GM can allow a success, even on a failed die roll, but add a setback or condition due to the bad die roll. e.g. PC wants to swing across the room on a chandelier and kick a bad guy into a pit. Instead of just failing, and not even being able to swing across the room, the GM can ask the Player, "Do you want to succeed with a setback?" If the answer is, "Yes," then the PC could succeed, but the bad guy grabs onto the PC's leg and now the PC is hanging off the edge of the pit and the bad guy is clinging to the PC's leg.
If you understand your scenario, you can move scenes around without damaging the pacing or flow. I was in a game run by Mike Mason and when the party broke up into 3 groups, he gave each group something to do, even the group that went to the library to do research (which generally is a die roll and a snore-fest). It was a published scenario and after the game, I read the scenario and found out that Mike cut-and-pasted various scenes, giving each group a scene even though they hadn't followed the required clue trails. It was masterfully done.
Pacing
Give players things to do. And try to even out each player's screen time. This is more important at a convention as you want everyone to have a good time. At a home game, you get to understand how much screen time each player actually wants. For long homebrew campaigns, one trick I use is to make each session or short scenario about one PC, so the focus is on that PC only for that session, but the focus over various sessions rotates through all the players. I ran a Ghost in the Shell game and each mission was tied to a different PC. I got this idea by watching Star Trek. There were Spock episodes, Kirk episodes, and Bones episodes, etc. So, why not have game episodes based on a specific PC? Rotate for fairness.
When a group breaks off to do research, it generally is just a die roll and then they wind up sitting and waiting as the other group goes and investigates a haunted location or follows a bad guy. The screen time becomes uneven. Unless the library group just wants to sit back and be safe, you can add some urgency by giving them some critical information or as Mike Mason did, make the adventure come to them. Have some bad guys lay a trap or follow them in the library. If I were an evil cultist, I would have someone watch for people researching ways to kill my cult.
I got some training from various schools of fiction. So, I'm a fan of a cycle of rising tension, periods of calm, and more rising tension going towards a climax. It's good to take a pulse of how the players are reacting, whether they are engaged or being bored.
Sense of Drama
If you have a good sense of the current pacing and the current tension level, you can then crank up the tension level, but how do you do that? You'll need a good sense of drama.
If the PCs are going to face the big bad, are they worried? Or do they think it's a piece of cake? If they're worried, maybe you don't need to do anything else. If piece of cake, maybe add some doubt. Do they have the right ritual? Do they know how to perform it? Are their ingredients correct? Are they being followed? Is the big bad mocking them? What do they not know? How do you signal this to the PCs? Have them notice they're being spied upon or attack them in their place of safety by some assassins (natural or supernatural). This will generally force the PCs to act sooner than later. They can't turtle up if their places of safety are compromised.
If the PCs are on the run, you want to make it more desperate, more hopeless. Why not add complications. Have someone be hurt, possibly from a side-effect of combat. Or give them some innocents that need to be saved. Do they take them with them? Or let them die? Are resources like ammo or food running out?
If the PCs are reluctant to face the climax, how do you make them invested in the climax? The best games give the PCs a stake in the outcome. If they don't face the big bad, something horrible will happen. In CoC, it's generally the end of the world, but that is too generic. But if the big bad starts affecting them or their loved ones in subtle ways first, and as the scenario progresses, they realize it's getting worse, then that'll get their attention. Threat to them and their loved ones always gets their attention.
Eternal Lies does this beautifully by attacking the PCs sources of stability and pillars of sanity throughout the campaign (my favorite Cthulhu campaign). Not only do the PCs face danger, but between scenarios, their loved ones are affected either subtly or attacked directly, so they must return and face the danger. "Once more unto the breach, dear friends, once more."
Understanding Human Nature
If the GM understands human nature, the GM can use that as examples during a game. When a PC makes a notice roll or a psychology roll, I love to give telling details about an NPC. It's great when the player understands what tell I'm giving them without having to explain it explicitly. e.g. "When he was answering that question, his hands were shaking as he was lighting his cigarette, it wasn't before." "He keeps on secretly glancing over your shoulder, as if he's expecting something, but you notice that he's doing that." "The nerdy bookseller didn't even flinch when you pointed the gun at him, something's not right." "Her voice changed, suddenly, her voice is more confident, you're not sure if earlier it was an act all along or if she suddenly got more courage." "He has his hands in his bathrobe pockets, holding something that's pointed at you, and you can tell he's very calm and not nervous at all, this is not what you expect."
These little tells, makes the game more interesting, it engages the mind of the players, makes them try to figure out what's going on. I played in one game where the GM had us explain what we were trying to do such as "I want to seduce a tourist" and he just had us make the die roll and told us, "You did it." I didn't like that game style. I prefer to at least role play some of the dialog or action before doing the die roll. Or even having a hidden difficulty level, so maybe you might have actually failed because the person being seduced is really a NPC plant that's going to betray you later.
What makes a Great Player?
Understanding the Game
A player needs to understand what game they're playing. Is this a min/max game? Is it an investigative game? Is this a humorous game? Is it serious? Is it a story telling game? What game are you in?
When you understand what game you're in then you can act appropriately. If it's a gritty spy game that's realistic, don't jump in guns blazing and be surprised when the Russian guards gun you down and then hunt and kill the rest of your team. Yeah, that'll ruin the game for everyone.
Flexibility to say, "Yes," and Improvise
Think if interesting things to do, but don't nerf the whole game for everyone else. If someone wants to infiltrate an enemy base by disguising themselves, how do you help them? Don't just say, "No. I want to just blow it up by tunneling underneath the bunker and planting explosives. My character lets everyone else do their thing and I'll do mine. As a side note, I blow everyone up including the other PCs." Why are you playing a RPG with other players if you're not going to interact with them? Maybe you can use your explosives skill as a diversion or you can put a suicide vest on the person infiltrating. Add to the plan, make it better, be flexible.
Able to Work with Others
Again, why are you playing a RPG with other players if you're not going to interact with them? Maybe if you think their plan is stupid or lacking, you can bring up your own plan or improvements. Figure out how you can make the game more interesting for yourself and everyone else too.
Sense of Drama
Sometimes people get into the D&D mindset of winning and losing. I think having interesting situations makes the game more memorable than killing that 3rd dragon and taking his loot.
Some people try to avoid conflict, but conflict makes things more interesting. In a KAP game I'm playing in, one of my PCs defeated a knight most of the PCs hated. They wanted to kill and torture him, but since I captured him, I got to decide what to do. The PC who captured the bad guy really didn't have a grudge against his captive, so I ransomed him and let him go. I got a lot of player grief because of it, but it was better drama and of course the big bad knight stayed as a major antagonist in the game and added more plot twists and side adventures. I went for better story, not for the easy win.
You're on the run and you run into some fleeing NPCs. Do you just let them try to survive by themselves or do you try to save them? Well, letting them die is the easy solution, but if you try to save them, it ups the drama and makes the game more interesting. Maybe they'll have a clue to help you? Maybe the injured will slow you down and let the bad guys catch up? Maybe they're bad guys in disguise? Maybe one of them is a replacement PC? Lots of options and more drama, making the game more interesting.
Paying Attention to the Game and to Details
In investigative games, it helps to keeps notes if your memory isn't that great. I have a pretty good memory, so I like to be in the moment and play. Taking notes takes you out of the moment.
You need to keep engaged and watch what's going on. I've been in a game where other players are either drifting off or paying attention to their smart phone, then when it's their turn, they ask, "What?" Then the table has to go over again what's happened. It kills the pacing and wastes time. Everyone's time is valuable, so don't waste other people's time and let everyone get more playing in by paying attention.
If your attention is focused, you'll pick up telling details and the game will be richer for you. Nuances will be lost if you're totally not focused and maybe when it's time to do that ritual, you'll suddenly remember a detail that'll help you succeed, instead of wondering why it failed spectacularly.
Here's two great articles on being a better player (links are below), language is a bit harsh though:
Call of Cthulhu 7.0 Edition
