World and lore
Find rivers on your map that run uphill or end in the middle of nowhere
A river that climbs a hill makes the explorer's travel notes absurd, and one that just stops raises questions the story cannot answer. Here is a check that walks a river cell by cell against the height of the land and tells you the exact spot where it goes wrong.
Check that the layers under the ground leave no gaps and get older downward
The miner digs through clay into a layer of fossils that the history says came later than the stone beneath it, or finds a hole in the world where no layer is defined at all. Here is a check for the ground's layers, with the exact depth where a layer starts and ends.
Suggest a travel route that keeps away from zones too strong for the player
A guide character should not lead a beginner through the dragon pass just because it is shorter. Here is how to weigh the danger of each place against the player's strength, choose the shortest route that stays within it, and say honestly when every road is too hard.
Check that treasure in a ruin could exist when the ruin was built
A sword from a people who arrived long after the tower fell lies in its cellar, and a careful player wonders how. Here is a check that ties every find to the people who made it, the years they lived, and the year the place was left, with a way to allow later scavengers.
Age an abandoned building so the roof falls before the walls
A hut left for a hundred years should not look like a castle left for a hundred years, and a roof should not hang in the air over a wall that has crumbled. Here is how to decay a building part by part so the picture of the ruin tells the right story.
Let a rumour spread from town to town, later and weaker each time
The player burns a barn in the north, and ten days later a stranger in the south mentions it, slightly wrong. Here is how to work out on which day each town hears of a deed, how much of it is still believed, and where it fades out.
Make the same deed legal in one province and a crime in the next
Carrying a certain herb is fine in the hills, taxed in the valley and punished at the capital, and the player should be able to learn that by travelling. Here is a tidy way to set the laws once per land, let provinces inherit them, and check what the guards take at a border.
Make sure a hidden place can still be found if a clue giver dies
The only hint to the hidden spring comes from one old woman, and the player's raid on the camp ended her. Here is a check that counts the independent kinds of hint for each secret that can still be reached, treating hints that can be lost as half a hint.
Name the player's settlement after what it is, not after its fences
The player built sixty fence posts and four houses, and the world calls the place Fence Town. Here is how to let the world's people name a base from what it really does, ignore decoration, name a mixed place sensibly, and grow the name from a camp into a town as it gets bigger.
Count how many extra shelters a long route needs so no one is stranded
On the road across the plains there is a hut at the start and one at the end, and a storm in the middle leaves the traveller nowhere to go. Here is how to measure the longest stretch from any point to cover and to get the exact number of places to add, including the ends of the road.
Let players buy back what they just sold, without making free money
Everyone sells the wrong thing by accident, so a shop should hold it for a short while. Done carelessly, that list lets the player earn gold from nothing or loses a quest item for good. Here are the rules for price, space, time limit and things that may never be sold.
Check that the gear a player can afford keeps up with each new region
If the next region's monsters are stronger than anything the shops in reach sell, the player is stuck without knowing why. Here is a walk through the world that buys what is affordable at each stop and shows the first region where the player falls behind, and by how much.