It's difficult to write about the philosophy of traditional RPGs because there are so many different kinds that are not the most popular one in the world: Dungeons & Dragons. For example, Call of Cthulhu, Pathfinder, Warhammer, and games from World of Darkness rank in the top ten that people play on Roll20 other than D&D, according to the VTT's ORR 2021 report, though these games make up only ~18% of a market share, of which D&D controls a whopping 53%.
There's also a question of what we mean by "traditional" in this sense. For our purposes, traditional games are older than their contemporary darlings in the indie space, and do not belong to the PbtA or old school traditions. We discuss PbtA and old school philosophies separately in this guide.
Given its market share, Dungeons & Dragons Fifth Edition (5e) will serve as our model for comparing OSR+ to the "traditional" RPG.
The Legacy of D&D
It's important to recognize that 5e carries with it the legacy of all the editions that came before it. It's not exactly possible to examine the contemporary philosophy of D&D separate from that legacy, and this is because no matter what the latest Dungeon Master's Guide (DMG) says, GMs all over the world learned to play in earlier editions before they came to 5e, and some of those editions are ones that the old school style seeks to codify, emulate, and revise.
The Yes, And
The Role of the GM
As the architect of a campaign, the DM creates adventures by placing monsters, traps, and treasures for the other players' characters (the adventurers) to discover. As a storyteller, the DM helps the other players visualize what's happening around them, improvising when the adventurers do something or go somewhere unexpected. As an actor, the DM plays the roles of the monsters and supporting characters, breathing life into them. And as a referee, the DM interprets the rules and decides when to abide by them and when to change them.
The Dungeon Master (DM) in 5e is no different than the Game Master (GM) in OSR+. Traditional games like 5e do not try to distribute control over the fiction across the table, and this is also the case in OSR+. Of course, with great power comes great responsibility: the DMG leaves out one additional role of the GM that's very important, and that's the role of kitten-corraler: you've got to manage a lot of mundane things like prep for each session, player personalities, and scheduling the game itself.
On Rulings Over RUles
The rules don't account for every possible situation that might arise during a typical D&D session. For example, a player might want his or her character to hurl a brazier full of hot coals into a monster's face. How you determine the outcome of this action is up to you [...] Dice are like rules. They're tools to help keep the action moving. At any time, you can decide that a player's action is automatically successful. You can also grant the player advantage on any ability check, reducing the chance of a bad die roll foiling the character's plans. By the same token, a bad plan or unfortunate circumstances can transform the easiest task into an impossibility, or at least impose disadvantage.
5e as written defers to the GM for fiat decisions when there are gaps in the rules, and this is consistent with the old school style and OSR+. However, this advice is at odds with the mechanical specificity of the rest of the game, which tries very hard to fill in those gaps with as many granular rules as possible.
The game is also indecisive about when you ought to make a ruling: the DMG offers three approaches to making rulings, but considers each one equally valid as far as running the game goes:
Some DMs rely on die rolls for almost everything.
Use dice as rarely as possible. Some DMs use them only during combat, and determine success or failure as they like in other situations.
Many DMs find that using a combination of the two approaches works best. By balancing the use of dice against deciding on success, you can encourage your players to strike a balance between relying on their bonuses and abilities and paying attention to the game.
In OSR+, you make a ruling in a very particular context: a ruling is the creation of a new rule to resolve action in the game in a way that is not explicitly laid out by the rules-as-written. And you only roll dice when there is a meaningful chance of failure for a hero. The GM doesn't really have other recourse to skipping a dice roll or making up a rule in OSR+, and that includes the so-called "rule of cool."
The DMG does offer the above advice about meaningful failure, however: "Only call for a roll if there is a meaningful consequence for failure," but a contradiction arises when you consider that directive in the context of the three optional approaches to rolling dice, outlined above.
Consistency in the Fiction
Whereas [players'] role is to create characters ... breathe life into them, and help steer the campaign through their characters' actions, your role is to keep the players ... interested and immersed in the world you've created, and to let their characters do awesome things […] Consistency is a key to a believable fictional world. [This] makes the players feel as though their characters are part of a living world that changes and grows along with them.
Who can argue with the notion that immersion requires verisimilitude? This is the same advice as Keep the World Alive and Give Them Layers to Peel in the old school style, or Make the World Seem Real, Make the Player Characters' Lives Not Boring, and Name Everyone, Make Everyone Human in the PbtA tradition, even though the former leans more simulationist than the latter.
Pillars of Play
As a starting point, think about your adventure in terms of the three basic types of activity in the game: exploration, social interaction, and combat. If your adventure includes a balance of all three, it's likely to appeal to all types of players.
While 5e devotes the vast majority of its mechanics to that third pillar, combat, this division of the types of play in the game aligns with the game modes in OSR+: Downtime is social interaction; exploration is exploration; and encounter play is combat. In addition to this, OSR+ introduces overworld play as a means for players to advance the narrative outside their heroes' perspective.
The DMG further breaks down social interaction into carousing, building strongholds, crafting, running a business, performing sacred rights, gaining renown, merchantry, and sowing rumors, however the DMG includes an interesting note:
An activity should never negate the need or desire for characters to go on adventures.
Put another way: since downtime activities of this kind are not encounters, they don't afford XP and thus cannot advance the narrative.
This is not so in OSR+, as each pillar of play offers the opportunity to grapple with story hooks that have the potential to resolve heroes' conflicts.
In OSR+, downtime activities are abstracted so that GMs can accommodate any sort of social activity that might need mechanics to accompany it: parley handles social interactions like carousing and sowing rumors; montage allows for activities like preparations over time: performing sacred rights, running businesses, building strongholds, merchantry, crafting. Other activities handled by downtime include journeying, recovering, monologuing, and supplying, and can include encounter play like social combat.
The same is true of exploration, which has its own set of abstracted actions as a game mode.
On the Fourth Wall
Metagame thinking means thinking about the game as a game [...] Discourage metagame thinking by giving players a gentle reminder: "What do your characters think?" You can curb metagame thinking by setting up situations that will be difficult for the characters and that might require negotiation or retreat to survive.
Unlike the old school style, 5e wants you to think in-character when interacting with the fiction. This is consistent with the point of view in OSR+ that you should encourage players to consider what their heroes are doing before they suggest a mechanic to resolve it, especially since that's your job as the GM.
The No, But
Play to Have Fun
Rules enable you and your players to have fun at the table […[ Ideally, players come to the gaming table with the same goal: to have a fun time together […] If you take away anything from this section, remember this golden rule: Inspiration should make the game more enjoyable for everyone.
It may sound pedantic to argue against the assertion that we play RPGs to have fun—of course we want to have fun when we play RPGs!—but all too often we see "RPGs are meant to be fun" as a justification for making rulings, fudging dice, or creating content that breaks the game. Obviously, we don't play RPGs for the same reason we play Monopoly, which is to torture our family members. And we're not here to tell you why you play RPGs. How could we possibly know?
What we can tell you is the objective of play in OSR+: we play to resolve our heroes' conflicts. Fun should be a side effect of trying to do that in the game.
In the same way, while the rules enable us to "have fun at the table" because they keep us from coming into conflict over what is permissible in the fiction, they don't exist to make the game fun. In short, rules that model the actions our characters take in the fiction make it possible to differentiate the game from other types of games like improv.
Core Assumptions
Gods Oversee the World, Much of the World Is Untamed, The World Is Ancient, Conflict Shapes the World's History, and The World Is Magical.
5e as a system serves a number of campaign settings, but Forgotten Realms is its crown jewel, and "heroic fantasy" is its default genre. A lot of content in the game directly imports assumptions from that genre, especially in the design of magic items and spells.
OSR+ does not make assumptions like these, as the core fantasy rules are meant to be "skinned" by the additive worlds of OSR+, which are like mini-campaign settings unto themselves. In the future, the system will also support scifi and modern core rules within the same framework, which will put it in the category as universal RPGs like GURPs or the Cypher System.
And while it's true that content like the default origins in the core fantasy rules are defined by the campaign setting A Quest of Queens, the system as a whole is designed to be "pluggable," such that you can replace Daemon, Nim, and Tarth with other origins in order to evoke a genre other than sword and sorcery.
On Pass-Fail Mechanics
You determine the consequences of attack rolls, ability checks, and saving throws. In most cases, doing so is straightforward. When an attack hits, it deals damage. When a creature fails a saving throw, the creature suffers a harmful effect. When an ability check equals or exceeds the DC, the check succeeds.
Mechanics in 5e are decidedly pass-fail, as is the case in the old school style. By contrast, mechanics in the PbtA tradition are almost exclusively of the "fail-forward" type, meaning they allow for success at a cost results.
The DMG does mention rare cases where a failure by 1 or 2 points may be interpreted by the GM as a form of success at a cost, as well as the concept of "degrees of failure," where a GM may opt to adjust the consequences depending on how badly a player character failed a roll.
Failure can be tough, but the agony is compounded when a character fails by the barest margin. When a character fails a roll by only 1 or 2, you can allow the character to succeed at the cost of a complication or hindrance.
Finally, the DMG discusses critical success and failure, though it offers no hard rules about how to approach it outside of GM fiat. Overall, these rules are all optional, require GM fiat, and are at odds with the extreme mechanical specificity of the rest of the game, which does not require GM fiat.
OSR+, on the other hand, offers non-binary success checks as a core mechanic that GMs can use alongside binary pass-fail mechanics like attribute checks. Additionally, the game also equips GMs with scene checks so they can resolve entire scenes in a single roll with the same gradient for success that a success check allows.
On Metanarrative Currency
Think of inspiration as a spice that you can use to enhance your campaign. Some DMs forgo using inspiration, while others embrace it as a key part of the game. If you take away anything from this section, remember this golden rule: inspiration should make the game more enjoyable for everyone. Award inspiration when players take actions that make the game more exciting, amusing, or memorable.
For all its talk of "adventure as story," Notably, there are of course optional rules buried in the DMG that allow 5e GMs to introduce "hero points," "healing surges," and "plot points" (which function essentially the same as fate points). the core rules of 5e provide players with no metanarrative currency except "Inspiration," which is used solely to grant advantage on individual rolls.
Metanarrative currency in OSR+ allows players to collaborate on the narrative, which is especially useful when swingy dice work against players in ways that may lead to unsatisfying conclusions for their heroes. If the objective of play in OSR+ is for heroes to fulfill their destinies, then it's fair game for players to "game" the system with fate points and story tags.
In 5e, however, that swinginess of the roll is magnified by the die being a d20 and all twenty of those die faces being equally likely to turn up. By contrast, in PbtA games the standard 2d6 dice roll mitigates that swinginess to some degree, since results tend to average to 7 (though that introduces its own problems, since in PbtA games, that means most rolls result in success at a cost).
On Adventures As Stories
Fundamentally, adventures are stories. An adventure shares many of the features of a novel, a movie, an issue of a comic, or an episode of a TV show. Comic series and serialized TV dramas are particularly good comparisons, because of the way individual adventures are limited in scope but blend together to create a larger narrative […] Like every story, a typical adventure has a beginning, a middle, and an end.(describes adventures as having "beginning, middle, and ends"
One of the ways in which 5e departs from the old school style is its treatment of adventures as stories to be crafted by the GM. The notion that the GM is crafting a narrative arc for the campaign is explicitly outlined by the DMG, in a way independent of the goals players may have for their characters or the emergent narrative. Specifically, the DMG advises to "Write down the main story arc of your campaign, and keep track of things that you hope appear in future adventures. Update it as the campaign develops, adding ideas as they come to you."
Consider that GMs are instructed to consider the theme of the campaign writ large:
A theme in a campaign, as in a work of literature, expresses the deeper meaning of a story and the fundamental elements of human experience that the story explores. Your campaign doesn't have to be a work of literature, but it can still draw on common themes that lend a distinctive flavor to its stories.
What's remarkable here isn't so much the suggestion that a GM should think about the theme of the campaign (this is no different in PbtA games, and to a lesser extent, the old school style), but the language of story structure that permeates the text. The DMG even goes so far as to have the GM consider where the narrative of should end when he first sets out to design the adventure:
The climactic ending of an adventure fulfills the promise of all that came before. Although the climax must hinge on the successes and failures of the characters up to that moment, the Adventure Climax table can provide suggestions to help you shape the end of your adventure.
In OSR+, we want to get away from thinking of the campaign as a linear series of plot points, or as a structured story with a beginning, middle, and end.
Instead, by creating nonlinear adventures, we present players with a series of interconnected "scenes" that amount to what 5e would describe as (mostly non-combat) encounters. Because each scene surfaces adventure hooks to other scenes, the progression through the web of the adventure becomes player-driven. Coupled with floating scenes and story hooks that can be sprinkled by the GM into these scenes, we're able to influence the emergent narrative while keeping the players in control of its direction.
On Player Objectives & Incentives
When players don't know what they're supposed to do in a given encounter, anticipation and excitement can quickly turn to boredom and frustration. A transparent objective alleviates the risk of players losing interest. [...] The trick is to not distract the characters from the adventure at hand. Designing an effective hook for a future adventure requires finesse. [...] To keep players from straying, save your best ideas for the very end of your adventures, or insert them during periods of downtime.
The DMG in 5e spends a great deal of time hand-wringing over ways to keep players "from straying" from the locus of the adventure, which as we've seen, is designed by the GM before the game starts as a "story arc" with a "beginning, middle, and end." To this end the DMG suggests using "adventure seeds" as a means for cluing players into what leg of the adventure to pursue next, but those seeds do not come from the player characters' goals, and instead only serve to bridge the gap between the adventure's objectives, which 5e privileges as the agenda of the GM.
Some players create their own objectives, which is to be expected and encouraged. It is, after all, as much the players' campaign as yours [...] Players who ignore objectives will have to deal with the consequences, which is another important facet of encounter design.
The examples the DMG provides for "linking adventures" titled "The Quest of Many Parts" and the "Agents of X" both take the approach that the adventure is driven by global concerns external to the player characters' goals, and so the need arises not to "distract the characters" from the GM's agenda, which may not have anything to do with the characters' goals.
Contrary to 5e and the old school style, OSR+ creates player investment in the world in session zero, when players create story hooks that both establish what players care about in the fiction and what goals they wish to resolve on behalf of their heroes. The GM's agenda (or the objectives of the adventure) is then built on top of those story hooks, so that there is no tension between what objectives the players may have vs. the GM.
Encounter Design
Encounters are the individual scenes in the larger story of your adventure [...] A well-crafted encounter usually has a straightforward objective as well as some connection to the overarching story of your campaign, building on the encounters that precede it while foreshadowing encounters yet to come. An encounter has one of three possible outcomes: the characters succeed, the characters partly succeed, or the characters fail. The encounter needs to account for all three possibilities, and the outcome needs to have consequences so that the players feel like their successes and failures matter.
There's a lot to say about encounter design in 5e, as this aspect of the game is central to how it functions. In some ways, an encounter in 5e is equivalent to a scene, although as presented by the DMG it is not required to surface adventure hooks to other encounters. Random encounters, for example, lack a connection to the "story arc" of the campaign by definition.
The DMG describes encounters as taking place in "adventure environments" that are usually arrayed to a fictional space with boundaries, which is oftentimes suitable for being represented by a literal map. This is traditionally the dungeon, but in 5e, other locales such as the wilderness, urban settlements, and unusual environments (like underwater or on airships) are outlined:
Many D&D adventures revolve around a dungeon setting […] Not every adventure takes place in a dungeon […] Encounters with monsters might seem unlikely within a city's walls, but urban settings have their own villains and perils. Evil, after all, takes many forms, and urban settings aren't always the safe havens they seem to be.
Because encounters are the primary vehicle by which characters in 5e gain XP, and because the way you source XP in the game is by defeating monsters, the game establishes a rhythm of adventuring attrition punctuated by video game-like "short" and "long rests."
Assuming typical adventuring conditions and average luck, most adventuring parties can handle about six to eight medium or hard encounters in a day […] In general, over the course of a full adventuring day, the party will likely need to take two short rests, about one-third and two-thirds of the way through the day.
In OSR+, the closest equivalent to this sort of game loop is the nonlinear path players take through scenes in the adventure web.
Unlike 5e, the majority of these scenes are not combat-oriented. Scenes in OSR+ can represent journeying, montaging, parleying, dungeon crawling, recovery, chase scenes, social combat, physical combat, or overworld play, among others. There is no way to calculate the number of scenes that can be "handled" in a day by player characters because progression in the adventure doesn't depend on the depletion of their resources (progression depends on the completion of story hooks). Furthermore, the path players take through the web of scenes can't be predicted in advance by the GM, and so there is no need to manage attrition as players advance through the adventure.
Encounter Balance & Attrition
There are four categories of encounter difficulty: Easy. An easy encounter doesn't tax the characters' resources or put them in serious peril [...] Medium. A medium encounter usually has one or two scary moments for the players, but the characters should emerge victorious with no casualties [...] Hard. A hard encounter could go badly for the adventurers [...] Deadly. A deadly encounter could be lethal for one or more player characters.
In 5e, the DMG spends many pages illustrating how encounter design can be reduced to a mathematical formula ("evaluating encounter difficulty" via the "challenge rating" of monsters) that can help regulate the attrition of PC resources as they advance through the adventure.
In this way, 5e ties character advancement to the defeat of monsters, which are the sole documented source of XP in the DMG. Despite that there are three pillars of play in the game: exploration, social interaction, and combat, the DMG speaks only to the defeat of monsters as the basis for calculating XP.
And while it's true that there are a few passages suggesting that GMs can choose to award XP for other types of encounters using the same tables as combat encounters (as well as alternative rules for milestone, session-based, and story-based advancement), the fact that all of these alternatives fit on a single page of the DMG as opposed to the number of pages devoted to designing encounters with XP based on defeating monsters illustrates which approach 5e was really designed for.
You decide whether to award experience to characters for overcoming challenges outside combat. If the adventurers complete a tense negotiation with a baron, forge a trade agreement with a clan of surly dwarves, or successfully navigate the Chasm of Doom, you might decide that they deserve an XP reward.
This leaves GMs with the correct impression that the default mode for encounters in 5e is combat, and so GMs must use attrition of PC resources to create tension in the game. One such method of attrition is introducing more (random) encounters to whittle down those resources:
Random encounters can drain the party's hit points and spell slots, leaving the adventurers feeling underpowered and vulnerable. This creates tension, as players are forced to make decisions based on the fact that their characters aren't at full strength.
And while the DMG suggests that not all encounters need to be resolved through violence, it also admits that most monsters are hostile and meant to be fought:
Random encounters need not be level-appropriate challenges for the adventurers, but it's considered bad form to slaughter a party using a random encounter, since most players consider this ending to be an unsatisfying one. Not all random encounters with monsters need to be resolved through combat […] That said, a random encounter table usually includes hostile (though not necessarily evil) monsters that are meant to be fought.
In OSR+, you don't create tension between encounters by the attrition of resources that benefit players via diegetic mechanics. That is, while depriving heroes of their HP, MP, and supplies will put them on edge, the resource to lack that terrifies players, going into a potentially perilous encounter (whether the danger is physical violence, social combat, or puzzles, etc), is a non-diegetic one: a dearth of story tags or fate points. This is because in OSR+, metanarrative currencies allow players to steer the narrative toward the resolution of story hooks, which are also the scarcest resource in the game.
Scenes, moreover, have no mechanical relationship to monsters. Instead, scenes may have a narrative relationship to story hooks. And because resolving story hooks embedded in encounters enable heroes to bring their characters closer to resolving their conflicts (which in turn gains them levels), players are automatically incentivized to complete encounters.
GM-to-GM Advice
To be clear, I do not think 5e’s attention to encounter balance is damning, or that the game is flawed for taking this approach. In fact, encounter balance in 5e is appropriate for 5e, given its overall game loop. Instead, I bring attention to it because its approach to character advancement and creating narrative tension is in stark contrast to that of the PbtA tradition, the old school style, and OSR+, all of which do not require “balance” when designing encounters, nor tie character advancement to combat.
Mechanical Specificity
A creature that comes into contact with green slime takes 5 (1d10) acid damage. The creature takes the damage again at the start of each of its turns until the slime is scraped off or destroyed. Against wood or metal, green slime deals 11 (2d10) acid damage each round, and any nonmagical wood or metal weapon or tool used to scrape off the slime is effectively destroyed.
Traditional games like 5e are notorious for their sprawling mechanical specificity. For players who enjoy crunch of this kind, it's something to be lauded! But in the context of the old school style or PbtA, it is not.
To be clear, there's a difference between a game with a lot of rules and a game that has a lot of mechanical specificity. PbtA games have a lot of rules (both player and GM-facing), but those rules individually do not have the same depth or specificity that traditional games tend to have. For example, a spell in an old school game might be a couple sentences long with few, if any, parameters, whereas a spell in 5e is typically several paragraphs long and specifies a lot of parameters with unique values: casting time, range, targets, components, duration, and the classes it belongs to. Add to this that some parameters of spells like areas of effect have real-world specificity that the DMG even admits sometimes requires just guessing at in the absense of visual aids:
Many spells and other game features create areas of effect, such as the cone and the sphere. If you're not using miniatures or another visual aid, it can sometimes be difficult to determine who's in an area of effect and who isn't. The easiest way to address such uncertainty is to go with your gut and make a call.
Typically, the purpose of mechanical specificity in a game is to close gaps that would require rulings from the GM. The problem is that the more sprawling and specific the rules get in any given subsystem, the less likely the GM (or his players) can hold that subsystem in its totality in their active memory—at which point, we have to ask ourselves whether the rules we can't remember needed to be there in the first place.
Most of the mechanical specificity in 5e granularizes combat and the specific fictional contexts that in other games would be handled with on the spot rulings or reference to a single global mechanic. 5e provides specific checks and procedures for everything from detecting hidden doors, how to handle foraging in the wilderness, passive perception, walking over frigid water, surprise, specific hazards in the dungeon like spider webs, and swimming to optional rules for facing, flanking, line of sight, cover, attacks of opportunity, reaction and ready actions, massive damage and injuries. And that is not even scratching the surface of monster stats and subsystems that contain mechanics for poisons, madness, social combat, or chase scenes.
In OSR+, we want to avoid mechanical specificity wherever possible. All spells, for example, are patterned after a global logic that can be groked by the GM after having the player read the one or two sentence description aloud. This spell logic allows the GM to reason their way to a ruling that's consistent with the core rules, without looking any rules up. The same brevity is possible in designing monster stats, thanks to NPC shorthand.
Because the only modifier in the game is +2 or advantage and disadvantage, situational contexts (such as those that arise in combat) can all be handled on the spot without reference to the core rules.
OSR+, unlike traditional games, embraces the gaps in the rules, empowering the GM to make common sense rulings using the core mechanics (attribute or success checks) instead of looking to the rules to handle edge cases.
On treasure & Power
As characters grow in power, their ability to change the world around them grows with them [...] The tiers of play represent the ideal milestones for introducing new world-shaking events to the campaign [...] Events need to grow in magnitude and scope, increasing the stakes and drama as the characters become increasingly powerful. [...] Create material such as adventures, NPCs, maps, and so on for one tier at a time.
Traditional games like 5e implicitly value the accumulation of treasure and power as a central tenet of play. As much as 5e professes to be about the three pillars of play (exploration, social interaction, and combat), it is mostly about acquiring treasure, trading in it, and accumulating power as a result.
Again: this observation is not an indictment of the game. The old school style also trades XP for gold, and so the concept of enterprising through dungeon crawling has been patterned into 5e before it was written. Nevertheless, the fact that the mechanics of the game promote the accumulation of treasure and power is not a given in other games, and worth talking about to make that distinction.
To start, the majority of the DMG (29%) is devoted to cataloguing magic items—about 95 pages of its 322. The game builds into encounter design the expectation that "intelligent monsters often use magic items in their possession, while others might hide them away to ensure they don't get lost or stolen," and maps the random allocation of treasure to the challenge ratings of monsters. Finally, GMs are asked to consider how treasure fits into the game world, since players may want to traffic in treasure as part of play:
In your campaign, magic items might be prevalent enough that adventurers can buy and sell them [...] Sale of magic items might be regulated, accompanied by a thriving black market. Artificers might craft items for use by military forces or adventurers, as they do in the world of Eberron. You might also allow characters to craft their own magic items...
Treasure is so prevalent in 5e that one of the few non-diegetic mechanics in the game centers on restricting the mechanical impact of said treasure—"attunement,” which artificially limits player characters from using too many magic items at once, lest their use break game balance. This is thinly disguised in the fiction as a function of the item bonding with the wielder, but it's not difficult to see why such a mechanic needs to exist when so many magic items add +X to player character's rolls, in a system that requires bounded accuracy to work.
5e promotes a need to accumulate power in order to play the game to its fullest extent, and this permeates all aspects of play, as the DMG cautions when GMs go about designing homebrew spells:
If a spell is so good that a caster would want to use it all the time, it might be too powerful for its level. A long duration or large area can make up for a lesser effect, depending on the spell. Avoid spells that have very limited use, such as one that works only against good dragons. Though such a spell could exist in the world, few characters will bother to learn or prepare it unless they know in advance that doing so will be worthwhile.
The suggestion here being that really unique ideas (such as a spell that would "work only against good dragons") are not worth pursuing in the fiction if they're not also optimal.
At its core, OSR+ resists the notion that character concepts needs to be optimal in order to be viable, or that players need to pursue the accumulation of power in order to play the game to its fullest extent. At 1st level, heroes are about as powerful as they're going to be for the rest of the game, and subsequent levels (of which there are only 10), offer only incremental improvements, like an additional attribute point or a new skill, etc. Classes and kits do not have tiered abilities that grow as the hero becomes more experienced, and no abilitiy requires prerequisities that can be unlocked later in the hero's adventuring careeer.
There are no spell levels in the game, magical treasures only provide heroes with very specific weird abilities (rather than provide mechanical benefits), and equipment is abstracted as supply you declare when you need it. The "gold" currency in the game is flat and lacks nuance on purpose, to keep the focus away from acquisition for acquisiton's sake, and on the stuff that really matters in the game: resolving story hooks to fulfill heroes' goals in the fiction.