TrippyHippy
Hero
I GM like that. It's my style! 
-
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Should a GM be allowed to arbitrarily make things up as they go along?
- Thread starter Dungeoneer
- Start date
ExploderWizard
Hero
Quite so. The key word here is arbitrarily. When content is created in harmony with the existing game world as the group understands it, then it is far from arbitrary. Extrapolating from what exists using common sense and an remembering to give the players AND the game world an even break is the heart of making rulings.
Story may be generated from game play, but in an rpg it is not the purpose of it.
If you make a decision based on what would be good for a story, then you have left strategic gameplay behind.
If Billy had played with a GM like that I wouldn't blame him for his opinion.
I must say, the whole ruined temple thing struck me as quite odd. Are there many of them cluttering up neighborhoods that real estate brokers are needed?
Back in my day, if you found a ruined temple and cleaned it out it was yours as long as you could keep it from becoming re-infested.
Buy a ruined temple?
After reading all eight pages in one gulp I admit I am not sure what the problem is.
A DM changing the rues mid game without warning for no other reason then he does not like them or he is pissy because the players are tearing thorough is finally crafted encounter is bad DMing and could be seen as arbitrarily changing the rules and making players feel powerless. As a player you plan what you are going to do based on the rules. I think most agree this is not good.
But having to make a decision on the fly when the rules don't cover a situation or are not clear is one of the jobs of the DM. Every DM in my group including me have one table rule and that is in a situation like that we will make our ruling and move on. Rules argument suck the fun out iof a game in no time. Aster the session we all sit and discuss it and make a decision how to adjudicate the rule in the future.
In our group there are often game discussions of the various DMs on our house rules we all have different ones. One who is DMing right now has the rule that no not named mook can confirm a critical he does not think a hero should be taken out by random orc number 3. While I agree to a certain extent I practice what is good for the PCs is good for the NPCs. Which is why the players in my game don't ask for vorpol swords. The thing is we share players and I have never heard the players complain about the difference in house rules.
One comment I read is that it feel arbitrary if the party wipes out an encounter easily to add thing to make it more difficult. First of all how would the players know this. They should not be seeing behind the curtain. Second I do this but I judge my players if they look like they are having fun I may extended the encounter on the fly. I have also been known to wrap up an encounter earlier than planned because I can tell the players are getting frustrated or I realize oops I made this way to hard. I feel that my main job as DM is to make the game an engaging challenging fun game.
If my players don't or can't trust me not to being doings just to screw them over then there is no point in playing. I am not against them I want them to succeed but I will run the NPCs in the manner that fits their intelligence.
I think some of this comes from playing with DMs who become adversarial it is not the NPCs against the party it is the DM and I have played with DMs like that and it is not fun because the DM holds all the cards it is an uneven match.
Billy may have heard the horror stories of bad DMs or may not really be aware of the game works. If that is the case inviting him to watch might help. But there are certain Billys of the world who have a major issue with what they see as loss of control and the lack the ability to really trust others. I have over the years played with a few of them They are poison at the table, They see every failure of their PC as the DM is against them.
A DM changing the rues mid game without warning for no other reason then he does not like them or he is pissy because the players are tearing thorough is finally crafted encounter is bad DMing and could be seen as arbitrarily changing the rules and making players feel powerless. As a player you plan what you are going to do based on the rules. I think most agree this is not good.
But having to make a decision on the fly when the rules don't cover a situation or are not clear is one of the jobs of the DM. Every DM in my group including me have one table rule and that is in a situation like that we will make our ruling and move on. Rules argument suck the fun out iof a game in no time. Aster the session we all sit and discuss it and make a decision how to adjudicate the rule in the future.
In our group there are often game discussions of the various DMs on our house rules we all have different ones. One who is DMing right now has the rule that no not named mook can confirm a critical he does not think a hero should be taken out by random orc number 3. While I agree to a certain extent I practice what is good for the PCs is good for the NPCs. Which is why the players in my game don't ask for vorpol swords. The thing is we share players and I have never heard the players complain about the difference in house rules.
One comment I read is that it feel arbitrary if the party wipes out an encounter easily to add thing to make it more difficult. First of all how would the players know this. They should not be seeing behind the curtain. Second I do this but I judge my players if they look like they are having fun I may extended the encounter on the fly. I have also been known to wrap up an encounter earlier than planned because I can tell the players are getting frustrated or I realize oops I made this way to hard. I feel that my main job as DM is to make the game an engaging challenging fun game.
If my players don't or can't trust me not to being doings just to screw them over then there is no point in playing. I am not against them I want them to succeed but I will run the NPCs in the manner that fits their intelligence.
I think some of this comes from playing with DMs who become adversarial it is not the NPCs against the party it is the DM and I have played with DMs like that and it is not fun because the DM holds all the cards it is an uneven match.
Billy may have heard the horror stories of bad DMs or may not really be aware of the game works. If that is the case inviting him to watch might help. But there are certain Billys of the world who have a major issue with what they see as loss of control and the lack the ability to really trust others. I have over the years played with a few of them They are poison at the table, They see every failure of their PC as the DM is against them.
Plaguescarred
D&D Playtester for WoTC since 2012
Yes, definitly! Its one of the power of RPGs in that the game is run by a person who can adapt the action going on and also make rule calls or spring new mechanic on the fly.
More rules-heavy games see less DM adjucation arise in this fashion, but no RPG is able to cover every situation or devise mechanic for all that can happen during a sessions and this will always exist to some extent.
More rules-heavy games see less DM adjucation arise in this fashion, but no RPG is able to cover every situation or devise mechanic for all that can happen during a sessions and this will always exist to some extent.
Summer-Knight925
First Post
The best way to view it is comparing GMs to Musicians.
Every Musician has a style, they acquire this from other musicians they like, personal experimentation, and personal tastes in music.
But do musicians just change music whenever they want?
As much of a shock it may seem, the answer is yes, musicians have the ability to change how a certain song sounds and thus alter the entire meaning.
Eurythmics song "Sweet Dreams" is not altogether creepy, the lyrics are more about heartbreak and how people suck.
Now enter Marilyn Manson's version, which goes from 'they hurt me people suck' to 'they're stalking me right now to hurt me I should buy a gun'
Was music changed?
Yes.
Was it broken?
No.
This is the important part of GMing and why I am using this analogy.
It's one thing to makeup rules on the fly, musicians improve from time to time, why not GMs?
Changing something to better suit the situation of a game is like changing a note in a song or the rhythm, etc. ect.
And musically, there are so many different genres and tastes in music that you can make anything into anything and someone will like it.
This doesn't mean it's for everyone.
As a GM, you are running a game, and thus you have your specific goals and concepts and ideas, as well as morals and beliefs on PCs, what they can and cannot do, and how to solve problems.
Can a GM change rules on the fly?
Yes.
And they should.
If a GM cannot alter rules for a situation to better suit the players, the encounter, and the problem, then they might not be that great of a GM.
Playing table top RPGs is a lot like being a pirate, and as Captain Jack Sparrow once said (and this is not an exact quote) the rules are more of guidelines.
In my group, we roll up stats differently to better create a heroic atmosphere for high fantasy games that are often deadlier than what the rules say it should be (characters fighting CRs higher than they should in the case of my Pathfinder game, but because of how their stats are, it balances out and creates the same challenge as if the stats were rolled normally, the only difference being you don't get useless characters at times). I have designed Archetypes specific for my own setting, magic items that suit the lore of the world better, spells that make sense for the world, things all GMs should do if they are as enthusiastic about the setting as I am about mine. This isn't bad, in fact this is what makes pen and paper RPGs so great.
However, I can see where 'Billy' may be worried.
A good GM alters the rules to fit the situation, but does so to encourage balance, fairness, logic, and fun.
A bad GM alters the rules off the cuff for no reason.
Being a GM has some requirements, it's a prestige class after all, and one of them is they cannot be chaotic evil. At least a good GM can't. As a GM you need to have reasons for what you do, logic first and foremost.
So the elven wizard player complains that his totally awesome description of hitting the ogre didn't kill it because he rolled poorly on the damage, does a GM change it to help this player?
I wouldn't.
I'd explain how their description is not 100% sound and that the attack the wizard made has variables, as represented by the dice, and thus rolling poor on the attack means that swinging your Master's sword in the fashion you did failed to cut through the thick hide of the brute before you.
This isn't changing the rules.
But what if the elven wizard player wants to use shocking grasp on the ogre from a few feet away since currently the ogre is standing in a pool of water?
I would either use the excuse "well the nature of magic is such...", or perhaps I am feeling the idea here, and would allow the wizard to use the spell, but it would do less damage and the Ogre gets a save against it. After all, water does conduct.
The important part, if the GM allows the player to use shocking grasp in a pool of water, is that this continues to work, and not just for the player, but for other spellcasters as well, and suddenly it isn't a snowflake encounter, but rather a table-specific rule that allows spell casters to do such.
A good GM doesn't change the rules whenever they want, a good GM changes the rules for a situation, and then keeps that ruling throughout.
I mean, imagine how much fun it would be to play a game of MTG and have the ref give a ruling on a card in a game, and then the next time you use the card in the same game, you are given a different ruling.
Every Musician has a style, they acquire this from other musicians they like, personal experimentation, and personal tastes in music.
But do musicians just change music whenever they want?
As much of a shock it may seem, the answer is yes, musicians have the ability to change how a certain song sounds and thus alter the entire meaning.
Eurythmics song "Sweet Dreams" is not altogether creepy, the lyrics are more about heartbreak and how people suck.
Now enter Marilyn Manson's version, which goes from 'they hurt me people suck' to 'they're stalking me right now to hurt me I should buy a gun'
Was music changed?
Yes.
Was it broken?
No.
This is the important part of GMing and why I am using this analogy.
It's one thing to makeup rules on the fly, musicians improve from time to time, why not GMs?
Changing something to better suit the situation of a game is like changing a note in a song or the rhythm, etc. ect.
And musically, there are so many different genres and tastes in music that you can make anything into anything and someone will like it.
This doesn't mean it's for everyone.
As a GM, you are running a game, and thus you have your specific goals and concepts and ideas, as well as morals and beliefs on PCs, what they can and cannot do, and how to solve problems.
Can a GM change rules on the fly?
Yes.
And they should.
If a GM cannot alter rules for a situation to better suit the players, the encounter, and the problem, then they might not be that great of a GM.
Playing table top RPGs is a lot like being a pirate, and as Captain Jack Sparrow once said (and this is not an exact quote) the rules are more of guidelines.
In my group, we roll up stats differently to better create a heroic atmosphere for high fantasy games that are often deadlier than what the rules say it should be (characters fighting CRs higher than they should in the case of my Pathfinder game, but because of how their stats are, it balances out and creates the same challenge as if the stats were rolled normally, the only difference being you don't get useless characters at times). I have designed Archetypes specific for my own setting, magic items that suit the lore of the world better, spells that make sense for the world, things all GMs should do if they are as enthusiastic about the setting as I am about mine. This isn't bad, in fact this is what makes pen and paper RPGs so great.
However, I can see where 'Billy' may be worried.
A good GM alters the rules to fit the situation, but does so to encourage balance, fairness, logic, and fun.
A bad GM alters the rules off the cuff for no reason.
Being a GM has some requirements, it's a prestige class after all, and one of them is they cannot be chaotic evil. At least a good GM can't. As a GM you need to have reasons for what you do, logic first and foremost.
So the elven wizard player complains that his totally awesome description of hitting the ogre didn't kill it because he rolled poorly on the damage, does a GM change it to help this player?
I wouldn't.
I'd explain how their description is not 100% sound and that the attack the wizard made has variables, as represented by the dice, and thus rolling poor on the attack means that swinging your Master's sword in the fashion you did failed to cut through the thick hide of the brute before you.
This isn't changing the rules.
But what if the elven wizard player wants to use shocking grasp on the ogre from a few feet away since currently the ogre is standing in a pool of water?
I would either use the excuse "well the nature of magic is such...", or perhaps I am feeling the idea here, and would allow the wizard to use the spell, but it would do less damage and the Ogre gets a save against it. After all, water does conduct.
The important part, if the GM allows the player to use shocking grasp in a pool of water, is that this continues to work, and not just for the player, but for other spellcasters as well, and suddenly it isn't a snowflake encounter, but rather a table-specific rule that allows spell casters to do such.
A good GM doesn't change the rules whenever they want, a good GM changes the rules for a situation, and then keeps that ruling throughout.
I mean, imagine how much fun it would be to play a game of MTG and have the ref give a ruling on a card in a game, and then the next time you use the card in the same game, you are given a different ruling.
valhallions
First Post
I couldn't agree more with you!
We as GM's are there to provide a great experience for the players and if you sometimes have to change things as you go then so be it. Sticking to the rules and not bending because "thats not in the book" is not only stubborn but can really harm the enjoyment of a campaign. Flexibility is key as long as everyone is having a good time then there shouldn't be a problem
Storminator
First Post
Despite the OP saying "arbitrarily" it seems his friend is really thinking "capriciously". This is a whole different ball game.
PS
PS
LordNightwinter
Explorer
As has been said, opinions like that have a lot to do with the games a player has experienced. I've had several people tell me they have had a terrible DM/GM in the past. The kind of DM that would kill them if they do something he doesn't like or flat out tell them 'No you can't do that because I'm the DM'. Much like Tywin Lannister said, "Any man who must say, "I am the DM" is no true DM."
Oh yes, I went there.
Oh yes, I went there.
Ahnehnois
First Post
In administrative law, there are judgements rendered for "arbitrary and capricious" behavior (which I suppose implies that those concepts are distinct but related). It does seem that when people raise this issue they are thinking more of the latter.
Sword of Spirit
Legend
These threads are great to get me thinking about how to be a better GM.
The degree to which I "make stuff up" is inherently related to the specific game. Some games require more of that than others. So I'm going to talk about how I like to do it in D&D.
I think, as others have said, that consistency is a key. If I'm going to make global changes to rules (house rules), I let the players know ahead of time. Otherwise they might create a character that doesn't function as expected. That is annoying. I always ask my DM to let me know what the house rules are ahead of time for exactly that reason.
Example from an upcoming D&DNext game:
2. Finesse: The finesse weapon property does not function if you are wearing heavy armor or using a shield (bucklers are allowed).
3. Single-Weapon Fighting: If you are hit while wielding a weapon in only one hand, you may use your reaction to increase your AC by 1 (potentially causing the attack to miss) provided you have not used your other hand to attack, defend, or cast a spell since the start of your last turn. When you propose this option, the DM will tell you if you were missed by only 1, so that you won't waste your reaction when it cannot work.
Players could be justifiably upset if they didn't know either of these rules. I have document with all 6 of the formal house rules presented to the players.
Other things that I find nice to have understood from the start are how the DM interprets and applies rules that tend to be treated differently by different DMs.
Example from general experience:
I like to secretly roll many skill checks so that players don't know if they succeeded or failed. This really adds to the sense of immersion for me, and I love it. There is no rule for or against it, so it's legal either way.
It wouldn't bother me either way on how my DM does this, although I'd personally prefer he kept some rolls secret. As a DM, I make a judgement call on whether or not listing off these sorts of stylistic techniques to the group prior to the campaign is going to be appreciated or just feel like a waste of time to the group, and then act accordingly.
Then we get to what I think many of us are talking about: creative application. This is where we take the rules as written and bend or add to, without actually invalidating the base rule.
Example from upcoming D&DNext adventure:
I'm planning to run Isle of Dread, and the players will arrive via a shipwreck. Since I've had a lot of time to work on it, I've done more prep than I usually do (I love to improvise). I've decided that the players who desire to will be able to make Intelligence checks (with proficiency bonus if they have training in and use navigator's tools) to figure out where they are on the coast based on their map, after a day of coastal travel. I will make the rolls for them in secret. If anyone who is using and trained in navigator's tools fails the check by 10 or more points, I will rule that they believe they know where they are (even though they are wrong). Those who aren't trained and fail know that they don't know. So if we have trained characters succeeding and trained character failing by 10, we will have two different sources confidently stating where they are, and none of the players will know who is right. Golden. Now the characters can discuss/argue/reason amongst themselves, or decide to go one direction or another until they find out who was right.
I've made two situational rules changes. The official rules would probably require a Wis check, but I rule Int makes more sense in context, since you are trying to figure out a puzzle from nothing but the visual clues, rather than keeping track of where you are and where you are heading. Navigator's tools still will normally use Wisdom, but I've set precedent that sometimes ability scores will work with different skills/proficiencies. I've also made proficiency or lack thereof have an effect on the results of the check.
Personally, I'd both appreciate my DM doing that sort of thing, and like to know ahead of time that he does it. As DM, I'd tell players ahead of time about these sorts of situational changes I might make, and how they might set precedents. In the specific instance, because it's more or less a one-shot with pregenerated characters designed to start up quickly, I won't bother telling them ahead of time. Instead I'll ask before starting another adventure or campaign if they liked those approaches or not. These changes set precedents, but since those precedents are purely in the hands of the DM (like setting DCs), they can't really be easily codified other than to say, "I'm ruling that I can do this. Anyone object to either precedent?"
Next comes the part that can get annoying if not handled properly: mid-session rules revisions.
Made-up Example:
In running a session of Next a PC mage blasts the heck out of opponents with Ray of Frost, so I decide that cantrips do less damage. Let's just make them scale the same as a cleric's divine strike, because I find that more pleasing.
This is a big red flag. I'd hate that as a player, and I wouldn't do it as a DM. Instead, I'd let the rules stand as they are, and after the session or adventure I'd approach the group with the proposed house rule and see how they felt about it
And probably the worst way of doing it would be the unstable rules syndrome:
Made-up Example:
Mid-session decide that the PC's rays of frost do less damage, but I let the NPCs cantrips keep doing the normal damage. When the PCs notice this, I change one or the other to match. Then I do something obnoxious like this later because I think that's how it should be.
... Needs no commentary.
Now, once you get past the rules you get into content creation. Part of being a GM is making up content. Unless you are using a published module, that is a huge part of your role. You make up NPCs, locations, story hooks, etc. Even in this though, consistency in style matters for trust.
Improvisationally adding or increasing challenges based on party effectiveness is something I personally do not like. I don't want the NPC to spontaneously gain extra hit points because we are whomping him, or a trap to appear in the next room. Players will pick up on this. For me, it reduces the trust that I have in my character's agency. It's like Elder Scrolls IV: Oblivion out of the box, where you end up with epic mudcrabs and bandits in full daedric armor (needless to say, I played it with a mod) because they just keep getting stronger to stop you from getting anymore effective. I want to know that the world is what it is, and I get to interact with it in a simulationist manner. If we are playing a narrativist game where the world is just a supporting figure to a story about the characters, I darn well better be told that from the get go (or know it is the case because we are playing an overtly narrativist system). But I'm talking D&D.
So I determine what the challenges are, and stick with it. That doesn't mean that I might not make them somewhat adjustable. For instance, if I didn't know how many players I was going to have in a particular adventure, I might decide that there is one bugbear present for each PC at a certain encounter. But IMO, this needs to be done pre-game.
Interpretation of setting is related to the above, but something that I'm not nearly as opposed to. With interpretation of setting you make judgement calls about dynamic events based on what seems most fun to the story or game.
Hypothetical Example:
For instance, if you know that there are such and so NPCs in a small village, or even that there are certain types of NPCs in a small villages, you can decide which ones the PCs run into when based on DM fiat (instead of or in addition to a random table). These are the sorts of situations where I might roll randomly on a table if present, but then may stick with the roll or change the result if I think it would be more fun in the specific situation (I do the same with random treasure tables--want the tables, but like to tweak results).
I've never heard of a player objecting to this sort of arbitrary judgement. The NPCs are all there (or potentially there by prior DM/adventure design), and the DM is simply choosing which elements to bring in when. This is a major part of being a good DM, IMO. I think part of the reason I consider this a good thing (unless used to the complete exclusion of all randomness--I like randomness in D&D events) is that it doesn't adjust the challenge. You aren't just deciding to make the game more difficult for them.
And finally, adding color is another essential part of making stuff up as DM.
Example made up right now:
Harold Uthgarden is the long-time bartender and owner of the Flaming Flagon Restaurant and Tavern. Harold is a slightly portly middle-aged man with tawny skin, dark hair, a short beard and an eye-patch. He offers a friendly grin missing a single front tooth. He always wear a white cooking apron while at work, primarily because he likes to pop into the kitchen and make food for himself. Harold is a bit prone to drink, and when drunk he seems to poor most of his brains on the floor. At least he's a happy drunk. Harold is a good-natured man, with quite a bit of wisdom to impart to those who earn his friendship.
I find that sort of thing to be a highlight of my DMing experience. I enjoy the improvisation and acting involved in making up NPCs on the spot. It doesn't bother me in the least when my DM does that either. It's a tactic that is most enjoyable from either side of the screen if the players can't tell which characters you made up on the spot and which characters were pre-designed. The only way I can imagine this being a bad thing is if a DM needs a bit of work on how well he accomplishes the goal. Perhaps he recreates the same 3 characters over and over again, or stops the game for 5 minutes to think up a name, or the characters he makes up never have any future relevance to the campaign, even if the players attempt to invest in giving them relevance.
So when it comes to content creation, unless your improvisation involves increasing challenges, I can't see that it would even need to be run past the players prior to the campaign. It's just a given and desirable practice unless you are using a highly structured adventure.
The degree to which I "make stuff up" is inherently related to the specific game. Some games require more of that than others. So I'm going to talk about how I like to do it in D&D.
I think, as others have said, that consistency is a key. If I'm going to make global changes to rules (house rules), I let the players know ahead of time. Otherwise they might create a character that doesn't function as expected. That is annoying. I always ask my DM to let me know what the house rules are ahead of time for exactly that reason.
Example from an upcoming D&DNext game:
2. Finesse: The finesse weapon property does not function if you are wearing heavy armor or using a shield (bucklers are allowed).
3. Single-Weapon Fighting: If you are hit while wielding a weapon in only one hand, you may use your reaction to increase your AC by 1 (potentially causing the attack to miss) provided you have not used your other hand to attack, defend, or cast a spell since the start of your last turn. When you propose this option, the DM will tell you if you were missed by only 1, so that you won't waste your reaction when it cannot work.
Players could be justifiably upset if they didn't know either of these rules. I have document with all 6 of the formal house rules presented to the players.
Other things that I find nice to have understood from the start are how the DM interprets and applies rules that tend to be treated differently by different DMs.
Example from general experience:
I like to secretly roll many skill checks so that players don't know if they succeeded or failed. This really adds to the sense of immersion for me, and I love it. There is no rule for or against it, so it's legal either way.
It wouldn't bother me either way on how my DM does this, although I'd personally prefer he kept some rolls secret. As a DM, I make a judgement call on whether or not listing off these sorts of stylistic techniques to the group prior to the campaign is going to be appreciated or just feel like a waste of time to the group, and then act accordingly.
Then we get to what I think many of us are talking about: creative application. This is where we take the rules as written and bend or add to, without actually invalidating the base rule.
Example from upcoming D&DNext adventure:
I'm planning to run Isle of Dread, and the players will arrive via a shipwreck. Since I've had a lot of time to work on it, I've done more prep than I usually do (I love to improvise). I've decided that the players who desire to will be able to make Intelligence checks (with proficiency bonus if they have training in and use navigator's tools) to figure out where they are on the coast based on their map, after a day of coastal travel. I will make the rolls for them in secret. If anyone who is using and trained in navigator's tools fails the check by 10 or more points, I will rule that they believe they know where they are (even though they are wrong). Those who aren't trained and fail know that they don't know. So if we have trained characters succeeding and trained character failing by 10, we will have two different sources confidently stating where they are, and none of the players will know who is right. Golden. Now the characters can discuss/argue/reason amongst themselves, or decide to go one direction or another until they find out who was right.
I've made two situational rules changes. The official rules would probably require a Wis check, but I rule Int makes more sense in context, since you are trying to figure out a puzzle from nothing but the visual clues, rather than keeping track of where you are and where you are heading. Navigator's tools still will normally use Wisdom, but I've set precedent that sometimes ability scores will work with different skills/proficiencies. I've also made proficiency or lack thereof have an effect on the results of the check.
Personally, I'd both appreciate my DM doing that sort of thing, and like to know ahead of time that he does it. As DM, I'd tell players ahead of time about these sorts of situational changes I might make, and how they might set precedents. In the specific instance, because it's more or less a one-shot with pregenerated characters designed to start up quickly, I won't bother telling them ahead of time. Instead I'll ask before starting another adventure or campaign if they liked those approaches or not. These changes set precedents, but since those precedents are purely in the hands of the DM (like setting DCs), they can't really be easily codified other than to say, "I'm ruling that I can do this. Anyone object to either precedent?"
Next comes the part that can get annoying if not handled properly: mid-session rules revisions.
Made-up Example:
In running a session of Next a PC mage blasts the heck out of opponents with Ray of Frost, so I decide that cantrips do less damage. Let's just make them scale the same as a cleric's divine strike, because I find that more pleasing.
This is a big red flag. I'd hate that as a player, and I wouldn't do it as a DM. Instead, I'd let the rules stand as they are, and after the session or adventure I'd approach the group with the proposed house rule and see how they felt about it
And probably the worst way of doing it would be the unstable rules syndrome:
Made-up Example:
Mid-session decide that the PC's rays of frost do less damage, but I let the NPCs cantrips keep doing the normal damage. When the PCs notice this, I change one or the other to match. Then I do something obnoxious like this later because I think that's how it should be.
... Needs no commentary.
Now, once you get past the rules you get into content creation. Part of being a GM is making up content. Unless you are using a published module, that is a huge part of your role. You make up NPCs, locations, story hooks, etc. Even in this though, consistency in style matters for trust.
Improvisationally adding or increasing challenges based on party effectiveness is something I personally do not like. I don't want the NPC to spontaneously gain extra hit points because we are whomping him, or a trap to appear in the next room. Players will pick up on this. For me, it reduces the trust that I have in my character's agency. It's like Elder Scrolls IV: Oblivion out of the box, where you end up with epic mudcrabs and bandits in full daedric armor (needless to say, I played it with a mod) because they just keep getting stronger to stop you from getting anymore effective. I want to know that the world is what it is, and I get to interact with it in a simulationist manner. If we are playing a narrativist game where the world is just a supporting figure to a story about the characters, I darn well better be told that from the get go (or know it is the case because we are playing an overtly narrativist system). But I'm talking D&D.
So I determine what the challenges are, and stick with it. That doesn't mean that I might not make them somewhat adjustable. For instance, if I didn't know how many players I was going to have in a particular adventure, I might decide that there is one bugbear present for each PC at a certain encounter. But IMO, this needs to be done pre-game.
Interpretation of setting is related to the above, but something that I'm not nearly as opposed to. With interpretation of setting you make judgement calls about dynamic events based on what seems most fun to the story or game.
Hypothetical Example:
For instance, if you know that there are such and so NPCs in a small village, or even that there are certain types of NPCs in a small villages, you can decide which ones the PCs run into when based on DM fiat (instead of or in addition to a random table). These are the sorts of situations where I might roll randomly on a table if present, but then may stick with the roll or change the result if I think it would be more fun in the specific situation (I do the same with random treasure tables--want the tables, but like to tweak results).
I've never heard of a player objecting to this sort of arbitrary judgement. The NPCs are all there (or potentially there by prior DM/adventure design), and the DM is simply choosing which elements to bring in when. This is a major part of being a good DM, IMO. I think part of the reason I consider this a good thing (unless used to the complete exclusion of all randomness--I like randomness in D&D events) is that it doesn't adjust the challenge. You aren't just deciding to make the game more difficult for them.
And finally, adding color is another essential part of making stuff up as DM.
Example made up right now:
Harold Uthgarden is the long-time bartender and owner of the Flaming Flagon Restaurant and Tavern. Harold is a slightly portly middle-aged man with tawny skin, dark hair, a short beard and an eye-patch. He offers a friendly grin missing a single front tooth. He always wear a white cooking apron while at work, primarily because he likes to pop into the kitchen and make food for himself. Harold is a bit prone to drink, and when drunk he seems to poor most of his brains on the floor. At least he's a happy drunk. Harold is a good-natured man, with quite a bit of wisdom to impart to those who earn his friendship.
I find that sort of thing to be a highlight of my DMing experience. I enjoy the improvisation and acting involved in making up NPCs on the spot. It doesn't bother me in the least when my DM does that either. It's a tactic that is most enjoyable from either side of the screen if the players can't tell which characters you made up on the spot and which characters were pre-designed. The only way I can imagine this being a bad thing is if a DM needs a bit of work on how well he accomplishes the goal. Perhaps he recreates the same 3 characters over and over again, or stops the game for 5 minutes to think up a name, or the characters he makes up never have any future relevance to the campaign, even if the players attempt to invest in giving them relevance.
So when it comes to content creation, unless your improvisation involves increasing challenges, I can't see that it would even need to be run past the players prior to the campaign. It's just a given and desirable practice unless you are using a highly structured adventure.
