Here is a rule from Call of Cthulu that I would like more game rules to state in bolded, underlined, and extra large print.

Automatic Actions

Routine physical and intellectual actions in routine circumstances always succeed. There is no need to roll dice to walk or run, to talk or see or hear, nor is there reason to roll dice for any ordinary use of a skill. But the routine may become extraordinary in a moment.

Call of Cthulu 6th Edition

Runeslinger pointed it out in a recent video about mechanisms intruding into the flow of play.

Routine physical and intellectual actions in routine circumstances always succeed.

It doesn’t get more clear and simple than that.

The first time I played CoC was with a Keeper who had never been a game master. He totally overlooked the rule and had us rolling dice for routine actions in routine circumstance quite frequently. It was annoying.

As a fundamental rule for all tabletop role-playing games, it makes a lot of sense.

Automatic success in routine circumstances is an implied rule in OSR games. It isn’t stated overtly because most designers assume that referees know that characters can do basic tasks without requiring a roll.

If there isn’t something preventing a character from inspecting a door they can inspect it.

If there isn’t something preventing players from using a tool like a hammer and spikes, they can use them.

We are in an era when many (if not most) role-playing games have made the game mechanisms the primary way players interact with the setting. Some players and game masters operate under the assumption that any time they use a skill that is on their character sheet, they have to declare they are using that skill and roll dice before the game master will narrate the result.

I think it is worth taking a moment to point this out for some of the gamers who are new to classic adventure gaming.

My Basic Assumptions About Fantasy Adventurers

When I run one shot games at conventions or game shops with people I’ve never gamed with before, I make a point of telling them some of my assumptions about their characters.

Swords & Wizardry is my default game. When I run that game or any classic variant of Dungeons & Dragons, I assume the following about player characters.

Your characters have all the basic skills necessary to live in a pseudo-medieval fantasy world.

Your characters know how to…

• Start a fire using flint and steel
• Identify common edible plants like berries
• How to change a wagon or cart wheel
• Discern between a riding horse and a war horse
• Identify the most common types of monsters (goblins, orcs, ogres)
• Set up a tent, tie basic knots, and use common household items

I assume that an adventurer is at least as capable as the average peasant. Anything a commoner in a medieval fantasy world would know how to do is probably something that I assume your character can automatically do in normal circumstances.

Failing at such tasks under normal circumstances doesn’t have consequences that are very interesting to play out. I’d much rather we use our time playing through situations where player characters will get into real trouble if they fail.

Your characters know lore about the world that you, the player, may not know.

It is reasonable to ask, “Does my character know anything about this?”

In situations where I think your character will know something, I may tell you that information without needing to roll dice. I like to give players a bit of exposition about the campaign world by telling them something that “everybody knows.”

If I think a particular piece of knowledge is something their character knows, I just tell the player without waiting for them to ask. “You are passing into the forest ruled by a powerful elf queen. Everybody knows that the elves ritually execute anyone caught damaging the sacred grey oaks.”

I assume that player characters have been told bedtime stories by their nan, or watched a play or puppet show performed by a travelling troupe. Folklore about monsters, ghosts, demons, dragons, and legends about ancient heros are stories your character knows but you may not. If I have some bit of lore in my setting I think a character would know, I tell the players that lore when it is appropriate.

I assume that wizards and clerics are literate. I assume part of their training involved learning some portion of the myth, legend, and history of the campaign milieu.

If there is a chance they might know something but maybe not then I’ll roll a die and tell you the player what your character knows. 

Meta-gaming is something I allow as in character knowledge.

Most of us know that silver damages or kills werewolves and vampires can be killed with a wooden stake through the heart, decapitation, or sunlight. We picked that up from a movie, play, or story.

A good example of game specific knowledge is the way you can permanently kill a troll. If trolls are a relatively typical monster encountered by adventurers, it’s reasonable to me that adventurers might learn that from more seasoned veterans telling tall tales of their exploits.

It is kind of a weird situation for players to pretend they don’t have this common knowledge. It often doesn’t make that much of a difference anyway. Killing a troll isn’t easy and just because you know what it takes doesn’t mean you have the resources to do the job.

I don’t hand players every bit of information. Some things are mysteries, have to be discovered, or learned through play.

The basic loop of role-playing requires that I tell players what their character sees, hears, smells, or feels.

That information has clues as to what is happening in the encounter or telegraphs danger lurking ahead. Those are the points where players can get into trouble if they don’t think through the situation and apply their player skills to the problem.

Often, information can be learned by simply asking the locals, paying a sage, research, investigation, or some other method through the play of the game. I encourage players to make an effort to gather information by taking direct action to learn what they can.

You don’t need to roll dice to get a direct answer to a good question.

I Don’t Play “Gotcha!”

The long and short of it is that I don’t play “Gotcha!”

If there is a skill that I think is likely to be something they can do without much effort, I rule that the thing they intend just happens. They may need some time or have to use a resource in order to do the task without fail but they can do the thing they want to do.

If a player makes a plausible argument why their character might know something, then I allow the meta-knowledge or tell them what the character knows.

There are many situations when players can interact with the setting or gain information that do not require a dice roll.

Players are well advised to take advantage of opportunities where routine use of routine skills in routine situations improves the chances of success in situations where there is some degree of chance with a potential for failure.