RPG Core Mechanics

There are a lot of RPGs out there, and each one takes a different approach to its core dice rolling mechanics. From those that want no dice rolls to super-crunch rules, it can be intimidating as a GM to pick up a new book and learn those rules for a one-shot or even a campaign. However, RPGs (and board games too) universally share the same base mechanics, with the dice being the major differentiating factor. If you can identify the dice rolls you need and your roll as GM at the table, it is a lot easier to speed through the rules and get to play the game.

Rolling 1 Die

Examples: Pathfinder, D&D, Gumshoe

This mechanic is one where you have to roll a die to determine the outcome of the encounter. Sure, the next roll may have more dice or less, but the core mechanic depends on that one die roll. Each side of the die has the same probability as any other (i.e. d20 has a 5% chance to roll a 1 or a 20). There is no real probabilistic average, since the likelihood of rolling each number is equal.

Pros: It’s simple to do, since you have a die roll, add a modifier, and do some basic math. You only have 1 die to roll, so you can keep track of your result and even use simple random number generators to simulate result.

Cons: Since each result is equal, you do not have a real ‘average’ die roll. Extreme success is as equally likely as extreme failure, and most games consider the highest roll an automatic success and the lowest roll an automatic failure.

Opinion: This is a great mechanic for a lot of games, since it’s easy to learn and run with minimal math. However, having a ‘passive’ score on any single roll is not truly representative of the potential roll you would get.

Rolling %

Examples: Delta Green, Outbreak: Undead

A very common mechanic is to have a percent success number on your character sheet you need to either roll over or under. Depending on either system, you modify the appropriate stats on the character sheet to make it more likely of success.

Pros: Percentiles gives a wider spread than the 1 die method, since each % is quantified instead of lumped together in increments of 5% or 10%. Also, because it is a success/failure roll, it is possible to estimate better the chance of success and modifying that roll to become better or worse where appropriate.

Cons: Once again, the probability does not entirely work this way, and augmenting a % roll can be tricky. What if a character gets their stats to 100% success? How does the GM deal with such a character who does not need to roll? You also have to evaluate how well a character does on such rolls (i.e. if you have a 60% is there a difference between rolling 2% under and 50% under?).

Opinion: This is a nicer system that expands the 1 roll die mechanic, but has much of the same issues. However, because it is a % roll, you can simplify with random number generators and assign simple modifiers without worrying too much about how unbalancing those things can become.

Dice Pools

Examples: Burning Wheel, World of Darkness

Some systems have players and GMs roll multiple of the same dice with a target number for success. You may need to roll over a certain number, than add together the number of dice that succeeded. This introduces a much boarder probability curve to the process, and can even introduce tasks that are nearly impossible to characters without making it actually impossible (i.e. if you roll the highest number on the die you still succeed even if the target number is impossible).

Pros: It gives a better average die roll, since you know roughly how often each die will succeed and how many dice you will roll for a given action. Most of these games also possess a mechanic where characters can exert themselves to get more dice for a roll and improve their chances of success.

Cons: Logistically, this is a lot of dice to manage, and also results in maxing a single group of stats and using those exclusively so you roll the maximum number of dice all the time. That’s similar to other games, however you must manage more dice at these tables when it happens.

Opinion: Better modeling of probability in games is always a good thing. If the number of dice don’t get out of hand, it helps GMs a lot to see how good a character is by seeing how many dice the player has on a roll.

Additive Dice

Examples: FATE, Iron Kingdoms RPG

These are systems that require multiple dice be rolled then added together to determine the base number before modifiers. Often they will form bell curves to specific results that a GM can use as an average result in planning their game.  Single dice and % games use the mean (lowest + highest /2) to simulate this but it doesn’t make that the average die roll, only the average of the possible results. Here, you have a die roll that will happen more frequently and can be planned around.

Pros: Follows statistics (mean, standard deviation, etc.) so a GM can plan what to expect from their players as the game progresses. If a player plans appropriately, they can move their mean forwards or backwards, making their character unique.

Cons: Any modifier to a dice roll can have a disproportionate effect. In a d20 game, a +1 is a 5% shift. In a 2d6 game a +1 can have a 10% or more shift and even eliminate possible failure in some cases. When using such a system, having failure and success conditions becomes very important, as is balancing bonuses.

Opinion: From a behavioral standpoint, this is a very good die roll system. It models averages better and makes small bonuses very important. However, mechanics need to be very carefully weighted to make sure a character does not get out of control and skew their personal dice rolling curve too much.

Active GM

Examples: Most RPGs (it would be easier to list the ones that don’t)

In most RPGs, the GM is an active participant in the dice rolling. They roll to see how well an NPC hits a player character, or contest player rolls. It involves a lot of dice rolling. The GM has to keep up on everything, from NPC sheets, stats, modifiers, etc. It is a lot of on the fly paperwork and math.

Pros: The GM has to keep on top of the game they are running, so they concentrate and prepare most scenarios ahead of time so they are not ‘winging it’ during the game.

Cons: The GM has to maintain more notes, and also spends a great deal of time on NPC rather than story. It is very time intensive at the table, and discourages free form GMing as modifying on the fly is not a beginner skill.

Opinion: This is a good system for most games, since the GM is just as much an active participant as the players. In some cases, though, the mechanics swap out when GM or player is an active participant or a passive one. The best example would be Saving Throws in Pathfinder/D&D. They are the only defense roll you make, while other defenses are fixed numbers.

Passive GM

Examples: Cypher System RPGs

In passive GM games, the GM is there strictly to guide the story and add conflict. They roll no dice actively against the characters, setting target number or successes for the players to meet. Most games can be run this way if the GM knows the average die roll the players need to aim for then adding any modifiers their NPCs have.

Pros: The GM spends less time ‘balancing’ encounters and focuses on the story aspect during the game. Combat is still an active component of the game, but since the players are rolling the dice, the GM makes them do the math and keeps a fixed number for them to beat.

Cons: Active participation of the GM can feel strange, especially when the players do not see the GM sorting dice. Most of these systems use fixed numbers for NPC stats, to if the enemy inflicts damage, it is generally a set number the character cannot resist without variability.

Opinion: This method reduces a lot of preparation time for GMs and time at the table while GMs do their characters’ math. For new GMs, this system keeps the same level of mechanics but makes it substantially easier.

Everything Else

Once you pick up on the core mechanic and your roll (see what I did there, it’s a pun) at the table, everything else is minutiae. Do you absolutely need to know every modifier for shooting from cover? Not really, because you roughly approximate it if the reference table is buried or the player doesn’t know. Can you wing attack and damage? These are usually straightforward, and you can design your game around avoiding making it complicated to start.

Try it out. Grab a new RPG you have been interested and see how it fits into these two criteria. Once you do, you should feel more confident in your abilities during your next game session.

Starting a New Campaign

Starting to work on a new RPG Campaign for a small group, I am left considering my options. Not only do I need to choose an RPG system but I need to design the setting. Do I want to go standard fantasy or maybe a modern urban adventure? It’s hard to say what’s best, but I have thought about the different components of setting design.

Eras of Play

Initially, consider when the setting takes place. We’ve had tens of thousands of years of cultural evolution and (hopefully) even more in the future. Are you looking at a period for your world that has an equivalent, or sometime that does not have a close facsimile to our world? Here’s my cheat sheet.

Time Description RPG Example
Primitive/Pre-History Sentient races are just learning the fundamentals behind technology and organized culture. Nyambe
Historical Writing has been invented and people are organized into subgroups to differentiate their status in society. Deadlands
Modern The world is as we see it now with only minor differences noticeable to passive observers. World of Darkness
Future Technology has evolved past what we know of it today, either to the benefit or detriment of the world. Eclipse Phase
Fantasy Magic is the key to your world and technology is either nearly non-existent or heavily dependent on magic. Dungeon World

Genres of Play

You must also decide the flavor your campaign will have. You CAN run a standard historical game, but is that going to be compelling? Probably not. It would be better if you introduce something a little more exciting, and here’s what I will typically choose from.

Flavor Description RPG Example
Horror Keeping your sanity and not being eaten are major motivators in a campaign like this. Call of Cthulhu
Superheroes Good and evil battle on massive scale that can barely be comprehended by normal people Mutants & Masterminds
Pulp Science meets Romance meets Punching Hyper-Intelligent Fascist Gorillas in the face! Spirit of the Century
Science Fiction Technology borders on the magical, as the boundaries between reality and what we can only dream of fall. The Strange RPG
Apocalyptic The world as we know it has ended due to catastrophe, and survival becomes the major motivator. Outbreak: Undead

Putting it All Together

Looking at these tables, I can see a lot of choices that would be fun to try out. Even looking at some of the premade settings I have, I can translate these into what I have here and make it more compelling of a setting for my players by GMing to those themes.

Having multiple Genres or Eras in your setting can also add to your players’ enjoyment. You could have a Primitive society in your Future setting, where a young race of people surrounds a hyper-advanced city a few miles away (i.e. Atlantis). Or add multiple genres, such as twisted demons who battle for control of a magic scarred solar system (i.e. Mutant Chronicles).

These are mainly guidelines to help you in building the background for your setting or translating what you read into simpler story seeds and plots. Your setting, from birth to play, is built on a foundation like this, and having a good foundation is the first step to an incredible campaign.

Movement in the Cypher System

On the way to Gen Con 2015, Matt and I talked about how to use the Cypher System in a dungeon crawl. We both really enjoy the diceless aspect of the game, and how easy it is to play. On the other hand, its use of distance is very fluid and not conducive to miniatures or tactics in dungeons.

What we decided to work out was how far a character could move based on their Speed Pool. Our calculations produced approximately 1 yard per Speed per round. Here’s the breakdown.

Maximum Speed Stat

Without using Cyphers, Artifacts, or any other outside effects, the highest Speed pool possible is by creating a Swift Warrior who Moves Like the Wind, then investing all bonus Pool points into Speed.

Bonus Total
Warrior Type base Speed 10 10
Bonus Points from Character Creation +6 16
Swift Descriptor +4 20
Moves Like the Wind Focus at Tier 1 +5 25
Moves Like the Wind Focus at Tier 2 +5 30
Moves Like the Wind Focus at Tier 5 +5 35
Tier 1 Advancement Bonus +4 39
Tier 2 Advancement Bonus +4 43
Tier 3 Advancement Bonus +4 47
Tier 4 Advancement Bonus +4 51
Tier 5 Advancement Bonus +4 55
Tier 6 Advancement Bonus +4 59

Usain Bolt – Fastest Man Alive

Using Usain Bolt, the fastest Olympian for the 100m, 200m, and 4x100m, as a benchmark for this level of Speed Stat, we are going to derive how fast he moves in a round (approximately 6 seconds).

Distance Time Speed
100m 9.58 sec 10.44 m/s
200m 19.19 sec 10.42 m/s
4x100m 36.84 sec 10.86 m/s
Average 10.6 m/s
Round 63.6 m/rd

Movement in a Round

We now know the maximum Speed Pool a character can attain ‘naturally’ and the fastest they can move in a short period of time. Taking these factors:

63.6 m/rd ÷ 59 spd/rd = 1.08 m/spd = 3.54 ft/spd

Considering that we don’t like decimals in calculating any RPG stats, and that there is also a Running Skill that is used to increase movement, we’ll call this 1 yard moved per Speed per round.

How to Use

From here, you have a character that has the potential to move almost 24 mph (38 kph) in a single round, without running!

That is insanely fast. How does this balance with the game, since such a character could outrun almost anything they are pitted against short of a car?

This version of Movement is tied directly to the Speed Pool. To start, make it Current Speed to determine Movement, so as the character’s Pool decreases, so does their maximum Movement. Next, sustaining this takes a lot of energy. Forcing the character to make Running Skill rolls each round beyond their Speed Edge, Effort, or Tier can also slow the character down. Finally, moving this fast requires complete concentration on the task, movement in a single direction, and a cool down afterwards. The character can be restricted to moving in one direction and a full round to slow down (at half their maximum Movement).


This sets characters to being equivalent to most d20 and similar tactical miniature games in mechanics. A base Speed 10 character would move 30 feet, much like your D&D medium-sized humanoid. It adds a degree of realism to it, as a character tires their Speed reduces and therefore their maximum distance. A few flaws to point out are that you are on the 1 Yard system, which can be a pain since we’re used to 5-foot squares. Also, if this is considered normal speed, you’re talking about 24 mph at Tier 6 as a character’s standard movement.

However, the design of this mechanic is for small dungeon rooms or hallways, and overall, it should provide a good house rule for those of us who want to take a favorite system to a favorite setting.

DIY Character Sheets

I have never liked the publisher created character sheets. Not that they are terrible, in fact a lot of them are very nice and easy to use. It’s more the way I like to use them.

When I ran a LARP, a player had developed a very cool piece of software using Visual Basic. It maintained your character database, allowed custom character sheets, and let you do whatever you wanted by adding more data to it or limiting access as you saw fit. Being spoiled that early in my GM career, when I moved on to other gaming tools, I never forgot how easy my life was back then.

Now when I GM, I like having the versatility to have my sheets do calculations for me and having a database of sheets I can easily grab from. Using PDFs means I must save them as PDFs or print them, not my preferred way of doing the work.

Instead, I create sheets in Excel or Word (mostly in Excel). I have a great calculation tool that does a lot of my work for me, it will populate cells throughout the sheet by just selecting a character’s name, and if I ever need extra, I don’t have to go hunting through a lot of files.

The key to creating your own character sheets is to prioritize what is most important to play to least. I generally try and fit all the mechanics on the first page, so a player (or GM) can quickly find what they are looking for in an encounter. Descriptions, backgrounds, flavor text, character portrait, etc. goes on a second page where the player can reference it, but it doesn’t get in the way. The last page is in depth mechanics for powers or equipment the player may need.

If you need to make a complex sheet, like one for The Strange RPG, look at how you want that organized too. I purchased specialized sheet protectors for that and tailored my sheets to fit in those so players can swap out recursion cards quickly.

What’s important is that you and your players can use them and they do what you want. If you’re going to stick with the same layout as the original character sheet, that’s fine too, but you should ask yourself why you’re doing it and make modifications as needed (like for expanded powers or advantages). One you make two or three or them, you’ll get the hang of it.

To start, here is a batch I have used for many Gen Con events. As I find more of the sheets I have created, I’ll upload them to our site. The publishers make these all available for free on their websites or DriveThruRPG as they are presented in their rulebooks, and I am not including any rules. If you want a much fancier sheet, I strongly recommend going to them for what they produced.

On the other hand, if you want the power of a workbook, I hope you like them!

Your Every Day Carry Gaming Bag

When you’re a Gamemaster, space is at a premium in your bag and on the table. You must consider carefully what is important and what you can leave behind, and it is a nearly continuous challenge. Running events at conventions make it even more important to think about what you need.  The basic items that every GM has (dice, rulebooks, pencils, paper, scenario notes) can be streamlined but beyond that, there is an entire world of supplemental gear you might consider.

About a year ago, I build my GM Every Day Carry (EDC). This small pack was something I could easily drop into my backpack or carry with very little effort.

As a player or a GM, I wanted something that would not take up a lot of room and I could grab if I was in a hurry. What I learned from stocking it, and then over time swapping out different parts, is what I’m going to share now. And, if you want to see what I put together, at the end of the article is my bag and what’s in it.


If you’re building your GM EDC, you need dice for yourself and maybe some for a player or two. I keep 3 complete sets of d20 dice (d20, d12, d10, d%, d8, d6, & d4), 2 sets of FATE dice, and a lot of d6s for games like Fiasco or Iron Kingdoms. This takes up part of a Crown Royal bag, so it isn’t a huge space eater. If you play games with specialized dice (like Fantasy Flight’s Star Wars or Dungeon Crawl Classics) you’ll need to expand this some. But keep in mind that you can keep a separate, smaller case that can be tossed in if you don’t play these games as often.

Please note, that if there is something you really need, like big soft foam dice because you are running for kids, or braille dice for the vision impaired, these are becoming more readily available online and in game stores. They may take up more room, but you need to get the dice you need!


A lot of games now use tokens. FATE, Cypher, Mouse Guard, and a lot of others use tracking chips at the table. I splurged and picked up a set of FATE coins and heart coins at Gen Con a couple of years back, not to mention a lot of sets of colored plastic chips. They take up about as much room as a partial set of d20 dice, but make tracking easier at the gaming table for you and your players.

Index Cards

Besides your notes, probably the most important writing surface you need are index cards. Character table tent with their name and description, secret notes to players, tracking initiative order, drawing out quick little maps, or making an inventory of loot in a room can all be done quickly with these. I keep a stack of index cards that are blank on one side and gridded on the other. This lets me build out a room if I need to for a dungeon or just make notes.


I keep a set of 7 pencils, a couple of pens (of different colors), a set of wet erase and dry erase markers (assorted colors again), and a Sharpie with thick and fine tips. In almost every game I’ve played in, I have used these, and other players have needed them. If you have a bag that has internal strapping, it’s easy to put these in the middle straps where they are out of the way but leave the larger pouches for bulkier items.


To make it clear, these do not go in your EDC. Your case will bang these up thoroughly. Instead, I began keeping a small miniatures case with a variety of miniatures if I don’t know what I’m going to be playing or the set that I’ll need. It’s about the size of the EDC, so it’s easy to toss in your bag with room to spare.


As a GM, I always have a physical copy of the game I’m running with me. This can get passed around the table, used by everyone, and it’s hard to lose. In some cases, I’ll copy important pages and attach these to character sheets to the book can be thumbed through only when necessary.

On the other side of this is what you do as a player. At a convention, you may know what games you’ll be playing, but sometimes you’ll just find a table and sit down. For this, I depend upon my tablet. I have a lot of RPG books as PDFs and these I upload to my tablet. I started doing this when I was a regular gamer at conventions playing D&D organized play and other big campaigns. Almost universally you were required to have the books with you that rules would come out of. My group would have a Sherpa bag with us just for this, and share it across the 3 or 4 of us. After a while we started photocopying the pages we needed, then switched to digital. It was a lot easier, and we could use our tablets for much more.


If you are going to be running a game, you need your notes. I have taken to keeping a lot of these on my tablet using OneNote, which lets me flip through tabs of different scenes, characters, or whatever else I need. But I do still like using paper, since that doesn’t need a battery. A folder, binder, or wire bound notebook are all best, but most important is that it is a place for your notes that you are comfortable with and can quickly reference and is just the right size for your game. You don’t need a 3-inch ring binder for a session, you need a small notebook or folder. Don’t overdo it.


This is the final item you might have in your bag. Maps are crucial to a lot of games, especially those that are tactical miniature based, like D&D, Iron Kingdoms, or Savage Worlds. All of these can be run without maps, but it makes it easier to visualize combat. If you’re getting ready to run an adventure and you know where your players are going, having these pre-drawn helps a ton. I have large 1-inch grid paper that I can fold or roll up to fit in my bag. But, if your players like being impulsive, I would suggest buying a wet erase battle mat that you can quickly draw on. These roll up nicely too, and even if you never use it, rolling it out is a RPG table tradition!

That is what goes into my GM EDC kit and bag. There is a lot of gear I could carry around (laser pointers, rulers, laptop, or Bluetooth speaker to name a few), but those are for those special occasions and stay at home usually.

If there is something I missed, let me know and I’ll see how to fit it in!