TTRPGs: Movement and AOEs on Hex Grids

This is written by someone who knows nothing of hex grids.

If you're using a square grid, then your range of movement resembles a square. This has the disadvantage of giving diagonal movement more value than horizontal movement alone or vertical movement alone.

The reality is that your range of movement should rather resemble a circle. This would give you an even distance in all directions.  If you can image, lay down a pencil and place one end against the base of your mini, then move your mini to the end of the pencil.

One compromise with a square grid is to treat diagonal movement with a different rule, but that's less intuitive, and who can really visualize what that might look like?

?

I think the hexagon is the best compromise. Note that a hex or square are just ways of dividing up a map into shapes with equal length sides so they can interlock. With a hex grid, you technically have fewer divisions (spaces) than a square map.

I think the hex has the unfortunate problem of making some concessions with how to intuitively draw the area of an area of effect or a line.  I don't know how you can you now portray a 10 x 10 area, which is what you're used to on a square grid, which was nice and easy. If every hex resembles a 5 square foot area, then perhaps you would want to describe the area of effect as a 15 square foot area, or a 20ft square area? Alternatively, you could still describe things in a radius just fine. But here's another concession you would have to make with radius or diameter areas. There are fewer hexes in a radius than hexes in a square, so a game indented for a square grid game makes the areas less potent because potentially fewer spaces can be targeted.

If you wanted to think about the areas as steps, then you would have:

5 sq ft: One square 

10 sq ft: Two squares

15 sq ft: Three squares (triangle)

20 sq ft: Four squares (diamond)

30 sq ft: six squares (triangle)

35 sq ft: Seven squares (hex or circle shape)

60 sq ft: Twelve squares (triangle, no points)

etc.

I would suggest that you would simplify AOW by suggesting that such effects can affect an area of X adjacent hexes. The word adjacent means that the hexes must be touching other hexes, and that the area must resemble an approximate shape.

Cognitive Load for GMs

Cognitive load describes how much information the working memory can hold at any given time. A higher cognitive load overwhelms working memory and can make running a game stressful when it doesn't need to be. You can start to forget things, like whose turn it is or features in a room you just deacribed. Simplifying any complexity in your games can reduce cognitive load and even speed up your game. For example, do you ever need to know a goblin's charisma score? Don't put it your notes! I want an intuitive game; Intuitive means something is so simple you can do it without thinking about it. There are many designs to simplify games. 

Target Number, Easy, and Hard

Take as a modern example, in Index Card RPG (ICRPG), there are no Armor Classes or Defense ratings for monsters. Instead, a single Target number is assigned to all actions in the scene. That's it! If ever a circumstance is present that would make a creature more difficult to hit, let's say one monster in a group is particularly better armored, then you would rule that attacking that monster is Hard, and the Target number to hit that monster goes up by 3. If a monster was blinded, then he would be worse at dodging, so he would be Easy to hit, and the Target goes down by 3. There are no prescriptions in the rules, just apply logic. Enemy in partial cover? Hard. The target also represents saving throws for the players. I love this idea so much. 

Hit Die (HD) of Monsters

In classic D&D, the number of hit die of a monster was a measure of its overall difficulty. It was the equivalent of the monster's level. The monsters to-hit bonus was equal to its number of hit die. 2 hit die means +2 to hit. It also had the save saving throws as a fighter of equivalent level. A 3HD monster saved just like a 3rd level fighter. As another design rule, the floors of the dungeon were called levels. As an assumption, the number of hit die a monster had was equal to the floor it would appear on. You could write the fighter's saving throws right on your dungeon map. All monsters had a d8 for hit die. I love these design ideas.

One Saving Throw

White Box is based on the classic D&D games. It creates a single Save for all monsters. That number changes based on character level or monster HD. Some creatures get a bonus or penalties to specific saves, but all saves use one number. For example, a fighter gets a +2 to saves against poison because they're tough. I love this rule.

Experience Points

Dungeon Crawl Classics says every encounter is worth between 1 to 4 EXP where the difficult of the encounter relative to the players represents the EXP value of the encounter. A 2 EXP encounter is an average encounter. Characters need 10 exp to level from 0 to 1st level. To get from 1st to 2nd level, they need 40 EXP. The game then uses a simple formula where the amount of EXP needed increases by 20 every level. So, it goes 40, 60, 80, 100, 120, etc. You'll never have to calculate monster EXP and then divide it, which isn't even hard. The hard part is pacing how quickly your players level up. I am looking forward to using this idea some day.

Initiative

Turns order is clockwise around the table is a rule that comes from ICRPG. It means no tracking initiative, and no rolling for initiative and recording everyone's rolls. I would change the rule about rolling dice to a coin flip to determine which side goes first. For example, on a d20; lower numbers (1 to 10) mean the NPCs go first, and higher numbers (11 to 20) mean the PCs go first. I would also waive the initiative roll when it makes sense that one side is obviously ready to act before the other. You will never lost track of turn order either.

One Action Per Turn

Older games keep it simple. On your turn, you can do one dedicated thing (an action). You can move up to your movement as part of your action. Basic Fantasy RPG and other games based on D&D B/X describes this. There is no double move (thank goodness!). This also makes your game go faster. You will never have to ask "is that it for your turn?" or "is your turn over?" You will know when someone's turn is over.

Close, Near, Far, Distant

Do not use precise, literal measurements for distances or ranges. Just use categories for distances and ranges. Close means you're so close you don't need to move; you can reach out and touch it. Near means something can be reached within one turn, so up to 6 squares or the length of a pencil. Far means something is further away than that, and you could impose a penalty for ranged attacks at this distance. Distant means something is out of sight or too far to clearly see, and so is effectively out of range. 

Minions

D&D 4e had a minions class of enemy who only had 1 hit point. Use minions, or track number of hits instead of damage for disposable NPCs.

Inventory Slots

Inventory management is unimportant unless survival mechanics are important to you, in which case having a limited capacity for carrying equipment forces players to prepare and to plan, and to set priorities. It keeps them from looting and hoarding even thing. Using slots rather than tracking weight and volume of equipment is a great idea for getting the experience of management without the more laborious bookkeeping. Different games do it differently. In ICRPG, 10 items are worn or carried, or stored in pockets, 10 items are in your backpack. If PCs recruit an NPC follower to carry their junk, this makes it easier.

Point Crawl

Hex Crawling is perfectly fine, but Point Crawling simplifies the process. Traveling somewhere is simplified into a number of turns where each turn represents a day or a portion of a day. For example, Location A and Location B have two routes in between them. Route 1 is 4 turns and dangerous, but Route 2 is 7 turns but safer. If the the party gets lost, add additional turns. That's it. Players can make choices. They have thr option to use turns to explore, search for resources, rest, they can skip a rest and force themselves to march, etc. Random encounters can threaten them.

Flow Charts, Not Maps

Maps in TTRPGs often represent a location and provide its scale using precise or literal measurement. This conditions you to think you need to track and present locations with literal, precise space. GMs simply do not need to literal space. Abstract space is easier. Instead, use flow charts where blocks represent rooms in a dungeon and the lines connecting them represent the hallways or corridors. Annotate your flow charts with the notes you need such as "entrace, 3 goblins, 1 guard dog". Entire towns can be represented as a grid where the different cells represent different districts or other subdivisions, and you would list the major locations such as shops or NPC homes, in each grid along with names of each.

Adventures, Not Campaigns

Why do GMs offer to run a campaign with a payoff in 6 months or longer? I was in a campaign for over a year that I joined a year after it began. What madness! It's more complicated to do all this, and it's a big ask of your participants. Just prepare your setting and NPCs as the players explore it. Prepare for this session, not six sessions from now. Make this session kick ass. Does no one realize 5e Curse of Strahd is side content for 7 levels, then you get to the good part which is Castle Ravenloft and Stradh. Eff that. Stop thinking so far ahead. That's overthinking. A series of adventures IS a campaign.

You Dont Need D&D to Play D&D

Gary Gygax has a quote that goes something like "the only secret DMs must not know is that they don't need rules." Gary Gygax knew that once you gave the rules away (or sold them), they were not yours anymore, and once GMs figured that out, they didn't need to give you any more of their money. Ever.

Gary Gygax was also famous for answering DM questions by asking "what did you do?" Then answering "that sounds good to me." Because Gary understood that he was not the authority on the rules. There is no authority except the GM at their table.

This is well understood by people in the hobby, but WotC / Hasbro didn't when they tried to deauthorize the OGL and again when they tried to turn D&D into a digital only subscription service. The changes they've been making to the content are nothing short of infantilization. They disclaimed Gary Gygax and others. They made other missteps. May they fail, and may their failure serve as an example to all other publishers in the future. They were poor stewards of the game, and they burned all their good will.

I don't like Shadow Dark because it's still too much like 5e, but I wish Kelsey Deon and her game all the best. I want her success to serve as an example of how to actually be a steward. Kelsey's game is a work of art and passion. May 5e 2024 fall into obscurity, and may games like Shadow Dark carry the mantle and the torch.

Why? Because you don't need D&D to play D&D. We want quality products that respect us and our legacy and our heroes and our intelligence. We don't need to buy anymore. We can make it ourselves. Buying a good product is still great thought! 

Managing Expectations in TTRPGs

Every time I've ever ran a TTRPG or been invited to play TTRPG, I have been disappointed by something, and I've dropped out of a few groups when it was bad enough. Managing expectations was a concern of mine from the very beginning. I think I've found the vocabulary that I need to describe concepts that GMs can and should use when inviting players to their game. These five items below should help you no matter what kind of game you're running. Explain these ideas to your players as early as possible.

1. Fiction Doesn't Mean Anything Goes

Have you ever told someone that their idea didn't make sense, and their response was something like "but it's [fiction / fantasy / sci-fi]" and the implications was that because something (the game) is fiction, anything should be permissible? Here's the counter argument. Just because something is [fiction / fantasy / sci-fi], that doesn't mean anything goes. Fantasy is fiction with fantastic stuff. In fiction, the limitations of the fantastic elements are established, and then the rest of the setting is assumed to be based in realism which we can all relate to. Note that realism here is not the same as trying to create a game or setting that simulates what is realistic. Note that the core rules do not say "disregard realism" or "default to realism", this is a ruling made by the GM; however, defaulting to realism as a rule of thumb is useful because it gives us a common understanding of how the world works where the rules of the game do not cover, and common understanding allows the GM to be fair and consistent in their rulings and helps the players to understand the limitations of what they can do and cannot do. This also has the benefit of simplifying the game.

2. Forget Everything You Know About X

Tell your players to forget everything they know about fantasy, sci-fi, horror, 5e, Faerun, Eberron, World of Warcraft, etc. Do not let them bring their knowledge or expectations about goblins or vampires or were-creatures or magic to your game. Tell them that in your setting, these things might work differently, and that by relying on their knowledge of other settings or pop culture can spoil the experience of your game for themselves. Tell them you expect them to figure things out through exploration, social interaction, and experience in play. Alternatively, this common knowledge can give us a starting point to understand a setting, and so you would want to provide them with a list of other fiction that has inspired your game like D&D's famous Appendix N. I personally do not like Tolkien's interpretation on elves, dwarves, and hobbits (halflings). 

3. Generic Setting vs Curated Setting

Tell your players that the GM is the curator of the setting. As curator, you decide what is appropriate for the setting and what is not. Tell your players whether you are running a generic fantasy setting that is a hodgepodge of fantasy's most popular ideas intended for mass appeal, or if you are running a game in a curated setting with select fantasy ideas intended for a niche audience. Even a kitchen sink setting can have a few restrictions for the sake of keeping the game simple to prep and run for the GM, and to create a more focused or cohesive experience for the players.

4. Don't Ruin the Mood

People go to see movies for the kind of movie it promises to be. An action movie that's just sad and doesn't have very much action would be disappointing. Now imagine going to see a horror move that has 15 minutes of good, uninterrupted comedy that breaks all the tension. Imagine going to comedy that has 15 minutes of uninterrupted violence and gore that leaves you feeling too disgusted to enjoy the rest of the humor. Some people think a TTRPG has room for everything, but for me, these are examples of ruining the mood. Tell your players to be considerate of the mood of a scene or situation, especially when the focus is on another player character. Tell your players the kind of mood or overall tone you want for your game. Do you want a game with a more serious tone like Lord of the Rings or Star Wars, or do you want a game with a whacky fun tone like a Marvels movie or even some cartoon. Tell your players to make a character who suits the tone of the game.

5. Compatible Playstyles

This is a response to the famous excuse "I'm just playing my character TM". Every player plays differently. Your playstyle describes more than what your fantastic race / background / class is, but also how you play it. Define how you want your players to play the game from the beginning. I want the players to have cooperative playstyles, but I find too often that there are players who have made characters who not cooperative. They make crazy, loner, mischievous, selfish, greedy, or violent characters. The intent may be innocent, but the effect is that their playstyle is incompatible with others' if not antagonistic. They inevitably complicate or ruin a scene or goal for another player and spoil the fun for them. The offending player provides the famous excuse TM, and they avoid taking responsibility or making changes to their playstyle. Don't give your players the opportunity to even make that character. At character creation, tell your players they need to make a character who can work as part of a team and play collaboratively. Suggest that the players all make characters who are morally compatible or who share the same beliefs, values, or goals.

There you go. These five rules should stop your players from making that chaotic neutral cyborg ninja turtle-kin from the future who multiclassed into batman and power rangers and who worships the god of math and speaks in the third person using a Jersey accent and he loves eating mustard by itself. As a bonus sixth tip, tell your players they need to make a likable character, and that is a concept itself that will have to be defined, but most importantly it means don't make an asshole or a dick.

Adventures, Not Campaigns

Adventures, Not Campaigns TM means planning and playing your TTRPG one small adventure at a time, not anticipating a grand finale and following a long six-month to a year plan to get there.

I don't know where this game will be in 10, 12, 15, or 20 levels. I don't even know if we'll all be playing for that long. I only want to plan enough content for 1 to 2, maybe 3 levels at a time. Maybe just the next session. I'm not saving my good ideas for when everyone is level 18. If I promise a dragon or a lich or a colossus, I'm putting that in now, not later. I'm not making the players fatten themselves up for 7 to 10 levels on the side content first. The main show is what's on tap, with side content available for curious or ambitious characters.

This is the promise of Adventures, Not Campaigns TM.

Players and the GM need to discuss what sounds fun right now, and the GM needs to prep that content. Once the players finish that, then we can discuss what sounds like fun next. This also gives us the ability to pivot more easily. If someone loses interest in the current conflict, or if more interesting conflict arises somewhere else, someone joins or leaves the group, we can adjust more easily.  Expectations can be met more regularly. Boring intermittent sessions can be avoided. The sessions will be focused on the immediate goals, not some major cataclysm one and a half years from now.

Here's how this works:

• First, the GM creates a local setting consisting of one town, one dungeon, and a wilderness in between, with room for expansion.
• Then, players create characters from the setting, with a goal, either short-term or long-term.
• The GM prepares the setting and the people in it, not the story. The setting will have:
• One major goal, possible minor goals on the side. Ways for the players to learn about them.
• One major obstacle, possible minor obstacles on the way.
• A reward or other motivation for the goal. 
• May also contain a condition such as a time limit or another restriction. 
• This is an adventure.
• When an adventure is completed, a new adventure will be created. A campaign is a just a series of adventures.

When I think about Curse of Strahd for 5e for example, I think "cool, let's fight Strahd", but in reality, we start off at level 1 or 3 and we do all the side content for several months until we're bulky enough for Strahd, then we fight Strahd! That doesn't sound like fun. Strahd should be an adventure, and the other stuff should be optional content. If Curse of Strahd was the Village of Barovia, Castle Ravenloft, and the wilderness in between, and if everything else was optional content, what percentage of people would pursue the optional content? How much optional content would they pursue? If you're playing your character, you want out of Barovia. Play your character and kill Strahd.

Elements of Story for GMs

GENRE
Fantasy and Science-Fiction are genres of fiction which describe the kinds of stories that we tell. Once the boundaries and limitations of the fantastic or sci-fi are established for a piece of fiction, the rest of the fiction can be assumed to resemble our real world. This makes up the internal logic of the particular fiction. In effect, just because something is fiction, doesn't mean anything goes. Breaking the internal logic is what fandoms call violating cannon, and it can cause disappointment. I don't know what expectations other people have when they hear generic fantasy, so leave your expectations behind.

TONE
Tone means the mood or atmosphere of the story. Take horror for example. Most horror tries to be scary and unsettling. If a horror film included something that does not compliment scary and unsettling, that could ruin the mood and spoil the experience for some. Tone can vary in type or intensity from scene to scene, but if the GM sets an overall tone for the game, create a character who suits the overall tone. The wrong action or speech (or overly optimized player character) can break desired tension of a scene or conflict at the expense of someone's enjoyment.

SETTING
The setting of the fiction has its own societies, mythologies, and history, and has its own rules, internal consistency, and internal logic. A setting is a further refinement of the genre and tone. Some settings are seemingly all-inclusive hodgepodges featuring the most popular concepts of a genre and have broader appeal, but they can be overwhelming and force people to play with ideas they don't like. Some settings are more curated and distinct with niche appeal, but they can be too restricting in their effort to focus on ideas that are more cohesive together. Tips for fitting into a setting: avoid pop-culture references and anachronisms; pick a modest name; pick a place of origin within the setting and learn one fact about the climate, society, politics, economics, religion, and military (or CSPERM).

THEME

Theme means an idea that is consistent in all parts of a work of fiction. Using one major theme in a setting, or a major location in the setting, can make the world or that part of the world has a consistent feel. In storytelling, the theme must be a commentary on the human condition, such as a particular human flaw or weakness, or the disadvantages having too much of one good trait.

CHARACTERS

The GM portrays the people who live in the setting. A simple character has a name, a job, a single word describing their general attitude, a simple physical description, and we assume they are otherwise a typical person for the setting. Most NPCs will be simple. A complex character has something they want and a reason why they want it (a goal and a motive). Major NPCs may be simple or complex. 

Provide the players with three archetypical NPCs: A patron who can give them work for rewards, a mentor or ally who can give them knowledge and tools to complete their objectives, and an antagonist who opposes their goals. Typically, your players will not care about your NPCs half as much as they care about their own PCs, and so your NPCs should be in service of the PCs.

CONFLICT

A story is about how the heroes resolve a conflict. In order to have interesting conflict, you need three things. First, you need a sympathetic point-of-view character, usually called a hero, with a goal. We need to know why the goal is important to the hero. Second, you need a more powerful opponent who opposes the hero's goal. The opponent must have the desire and the power to stop the hero in order to be threatening and to create a sensation of uncertainty. Third, there must be consequences for failure which creates tension, which we call the stakes. If the hero fails and nothing happens, that's boring. Why would the hero and the player who is portraying the hero care? To create conflict, follow this process:

1. Ask what the player character's goal is. Figure out why is it important. Bonus: Make it a once-in-a-lifetime opportunity. Make sure the player knows that if they fail, there won't be as good an opportunity for a while.

2. Create a tough NPC who functionally stops the hero from achieving their goal. The nastier the opponent, the better. Bonus: Find a way to make the relationship between the hero and opponent personal.

3. Add consequences for failure. The more severe, the better. Bonus: make the stakes personal for the hero.

CENTRAL TENSION

Absolutely put one of these in your setting! A central tension is a single major conflict that permeates entire setting, like a major change in government or religion, a new major war, a recent or looming disaster, etc. Now give every NPC an opinion on the central tension. Just like in real life, some people are opposed to war, some support it, some have mixed feelings. People holding the same positions can have differing, personal reasons for their positions. It will make the setting feel like it has depth, and it will add complexity to your non-player characters.

Rules for Character Creation

Characters must suit the setting and tone of the game.

• Be mindful that playing a joke character when the everyone is trying to have serious tone, or vice versa, can ruin the mood and spoil others fun.
• Bring a fantasy character to a fantasy, bring an adventurer to an adventurer, etc.
• Your character is from the setting, and so your character would have values and beliefs of a typical person in the setting, not modern-day earth.

Characters must be able to work as a team. 

• The intent is to foster collaborative playstyles rather than adversarial playstyles. Consider creating a character who is either a friend or family of another player character, or an ally with common loyalties, goals, and/or values.
• No anti-heroes, loner characters, or overly greedy or selfish characters.
• The character's morality or alignment must not be incompatible with the party.
• Don't commit to your character's quirks to the party's detriment.

You are an ordinary person from the setting.

• An ordinary person means a regular dude, not a caricature or parody
• You do not start out great or heroic but have the opportunity to earn greatness.

No backstories.

• The first few play sessions will be your backstory where an opportunity or conflict has come along, and now you're an adventurer.
• All participants begin the story with the same information and understanding, which can help manage expectations. They learn about the world together and figure it out together.
• Character's change over time can be better appreciated because each of them will be a point of comparison to the others.
• This is also about simplicity; the GM does not have to weave multiple backstories together.

Characters must be ambitious.

• Each character needs a long-term goal, and they need to pursue their goal through play. Work with your GM to create a goal for your character that you think is fun and that suits the game.
• Simple goals are great. Finding treasure or solving a mystery are excellent goals.
• The intent of PC goals is to make sure that the GM is preparing content that the players find interesting. 
• When a goal is achieved, the player must find a new goal for their character with input from the GM.

If your character dies, create a new one using the same rules.

• At the start of the game, create a backup character who has the similar origins and etc. as the party for cohesion, and keep them on the metaphorical bench until they need to be swapped in.
• An established NPC ally of similar experience to the players can make a great replacement PC.

Pop Fantasy or Popular Fantasy

If generic means a work of art that is typical of a genre, where genre means a style or category of storytelling, then consider the following:

Fiction may be considered fantasy or a subgenre thereof when it has ANY supernatural stuff present (example Buffy the Vampire Slayer). Once you define the limitations of the supernatural stuff, the rest is assumed to be similar to our real world as a point of reference.

Another way to think about it is Fantasy is a genre of speculative fiction where we take an idea, such as "what if there were magic kings on Earth," and we speculate on the idea in story form.

Given the above, the scope of Fantasy as a genre is very, very broad. Generic Fantasy is oxymoronic. I think what one might intend when they say generic fantasy is what the perceive to be popularly consumed by a casual audience, or a core audience. So, pop-fantasy is probably a better term. Pleb or Plebeian Fantasy or Pedestrian Fantasy if you wanted to be de derogatory.

But this is still not clear enough because I don't know what you think is pop fantasy, and I don't expect you to know what I think is pop fantasy.

Monsters in Fiction

What is a monster? Monsters are the personifications of things we fear and the unknown. They are not people. They are not intended to be or represent people. Monsters are placed into stories that try to describe things that go bump in the night and to evoke some macabre thrill, fear, or disgust in the audience. Monsters are dangerous and opposed to mankind. Either they're malevolent or simply indifferent to our suffering. They are characterized by extreme vices, strange powers, and mysterious weaknesses. They are meant as obstacles for the brave or wise to overcome, avoid, or flee from. Sometimes, the innate inhumanity they represent reinforces our humanity.

In the context of literature, a foil is a type of character who is used to contrast another character, and the effect of using a foil is to emphasize specific characteristics of one or the other character. Simply put, a good character's goodness is emphasized when compared to a bad character's badness. Monsters are the foil of humanity, and so it is inappropriate to humanize them. To humanize the monster is to make it into a new variety of a human with a variation on human morality and human thinking and human feeling. It suggests that on some level, every thinking thing is similar or the same. To do this is reductive to the purpose of monsters. Humanizing monsters takes away from their potential for mysteriousness and alienness, and it minimizes the horror of the unknown that they represent. The audience is meant to hear the pitter patter of its nails in the dark or its grim laugh, and to see the signs it left behind, not to learn about its complex social order and psychology. For some audiences or gamers, this is the premise of monsters that we desire. If you want to treat monsters as people, you ruin this premise of monsters for the rest of us, and you are a spoil sport. 

Were I to write my own TTRPG with a monster book, this is the text that would precede the rest of the book. I would elaborate with this. The lore of a monster is what is known about it, or thought to be known, by people in the setting. Lore is therefore incomplete and not guaranteed to be true. The Game Master or GM, being the curator of their game and setting, may change lore to suit it. The characters in the setting may be assumed to have no knowledge of the lore, and so they have to consult with experts. The characters must seek out and arm themselves with knowledge in preparation for their confrontation with danger. Lore is therefore earned by a process of discovery, and may require significant effort or cost or sacrifice. The stat block is a way of mechanizing the monster for play. Monster stat blocks remove the abstraction and mystery, and so they are metaknowledge, and not to be used as knowledge known by any ordinary character. In general, it is not within the spirit of the game to play your character using knowledge that you have that your character doesn't have, and is in effect cheating or spoiling the game as one might spoil the ending of a film for yourself or others. Players fear what they don't know. If fear and discovery would enhance a portion of your game, then the GM is encouraged to create their own monsters and to never use monsters as they are purely presented in the rules.

The reason why I would write a monster book for a TTRPG is so that I could write it with my desired premise built in. When you play a TTRPG such as D&D 5e for instance, it's fair to say that you can modify it however you want, but it's also fair to say that people have expectations for individual games, and when they're invited to play 5e, their expectation is to play with the 5e material as it is presented, and so they might be averse to any changes. The introduction to my monster book would be intended to prime my readers for my concept of monsters rather than theirs. If they agree to play their game using my monster book, they are agreeing to my premise, not theirs. I would explicitly address that my conception of monsters might be incompatible yours. If you try to seduce the dragon, it will automatically fail and for that turn, you will be vulnerable to dragon meaning you don't benefit from your armor or saving throws.