OSR games ostensibly care about player agency as one of their core principles.
Player agency can be defined as players having full control and responsibility over their own characters that the GM cannot interfere with. Ways GM’s typically interfere with player agency are by railroading players to certain destinations, for example by forcing players to save the village even if they would rather run away from it. By using techniques like ‘quantum ogres’ in which whatever direction the players go in they will face the same encounter and by extension any form of illusionism where players are given a false choice. Or simply by the GM fudging a dice roll, so that the choice the player made to attack a deadly monster is obsoleted when that monster cannot kill them due to GM fudging.
OSR games frown on this and instead encourage play where players are able to make meaningful choices for their characters within the world. Whilst the GM still has responsibility over the world it’s up to the players what they do within it and the GM acts as best they can as a ‘neutral arbiter’ of the game.
As a result OSR games tend to emphasise game structures that facilitate sandbox play in the likes of hexcrawls and dungeon crawls. They utilise a lot of randomisation mechanics, such as random encounters, reaction rolls and random treasure and monster placement to encourage the GM to allow player agency and not pre-script game situations. The GM is often ‘playing to find out what happens’ much like the players are.
There’s an interesting juxtaposition between the amount of freedom and agency given to players in OSR games and the limited amount of power in terms of mechanical ability characters in an OSR game have compared to other editions of the game, which can at first glance seem like a contradiction.
For example in an OSR game character stats are often randomly determined in order, taking those character build choices out of the player characters. Beyond that OSR characters will have far options and mechanical abilities.
A Magic User in an OSR game will often start with just 1 random spell they can use per day and D4 hp. In 5E D&D a Wizard starts with about half a dozen spells, can infinitely cast 3 cantrips per day and can cast 2 level 1 spells each day, starts with at least 6 HP assuming an average con score, and gets additional abilities and skills conferred by their race and background choices.
If our game cares about player agency, why do OSR games give characters such a limited amount of mechanical options to exercise their agency? Would you not be more free in a game if you had more options as you do in say 5E?
Well, not quite.
For one building a character is not the same as having agency within a game itself. The character building occurs outside of the game, it can be a lot of fun turning all the bells and whistles to design a character but it has very little to do with actually playing the game of D&D where you actually have to make active decisions in the moment for your character.
At its extreme this level of character building actually limits agency because character builds require a certain ‘white box’ perfect scenario to work effectively. You have to make the assumption that the game will include a set of perfectly tailored and balanced encounters that your character can defeat. But if we are to set up those encounters in a game we’ll be railroading the players hard to enforce them, rather than utilising the aforementioned sandbox techniques like the random encounters where a player may face the likes of a Dragon which their build is not equipped to deal with because it can only function in a limited parameter.
Agency is further predicated on the players having meaningful choices within a situation. If a character such as a Wizard should always cast a cantrip like mage hand to inspect a potential trap, or always cast Leomuds Tiny Hut for the group to rest in, then the player only has the one choice within a situation. Extrapolate it to the increasing power level of characters in a game such as 5E with a wide range of powerful abilities and the game becomes one of pressing the correct mechanical skill or spell button to solve the problem rather than having meaningful choice within the world.
Abilities such as the Rangers favoured terrain obsolete whole portions of decision making for players as they ignore key wilderness survival mechanic, effectively hand-waving over the players agency in those situations. Yes the player still had the agency of choosing the Ranger as a class, but this is no different from the illusionist GM presenting the players two false paths and giving them the same encounter in both. It’s just extrapolated to mechanically encompass the entire system.
Furthermore when we add the likes of a skill and feat system into the game we are effectively limiting player choices by saying that only X class with Y skill & feat combination can do a certain action. Though 5E isn’t as egregious as former editions of the game in this regard it still includes both of these elements which factor into limiting player agency.
Skill systems in general can also limit player actions towards simply pressing the correct ‘skill button’ within an in-game situation rather than describing what their actual actions in the game are. Even if a player does describe their action if these actions are always just resolved via whatever arbitrary skill feels like it fits we come to a situation where all that really matters is the characters skill bonus in a certain area and players are discouraged from trying actions that they don’t have the required stats in , further limiting their agency.
So we see the more powerful characters are, the less agency players often really have beyond an illusion. This also causes an escalation in terms of the GM attempting to match the players increasing range of abilities, this escalation can only ever be enforced within mechanical terms and the GM ends up having to use railroad techniques like forcing the players into constant ‘anti-magic zones’ to make it more difficult for them to utilise their powerful array of spells and abilities to bypass decisions in the game. This makes it difficult to create organic situations for the players to deal with through their agency alone as the GM is constantly in a cold war of sorts with the players as they both build up their collection of arms, which often culminates in incredibly adversarial gameplay.
To contrast OSR game-play gives players a much more limited toolkit to play with but through that limitation they are able to come up far more often with varied and creative solutions to in-game situations as they cannot solely rely on their characters power level to carry them through and therefore have far more agency in how they approach situations within the game not being limited by the heavy mechanical restrictions within the system.