The addition of “irrelevant” details adds local colour to a campaign world, giving the impression that the DM has thought very deeply about the history of even the smallest architectural feature.

A (fairly sketchy) outline of a one-off adventure I ran based around the (time-honoured/hackneyed) Tunguska Event of 1908. As such it is quite specific (hopefully not hackneyed) and will probably best serve as a specimen for dissection to get those parts you can use in your own adventures. But then this is an Ideas Guild after all...

The mystery of fyre is one which has much occupyed my studies and the studies of men before me. ... I have concluded that fyre is the product of Fyre Antes.

Professor J Klewlise, "On the nature and origin of fyre" (1542)

A mysterious quarry. Feel free to suggest explanations - it's just an eerie thought that struck me that I intend to play with.

I don't know if I posted about it before, but I have always wanted to run an adventure set in a library. The following is a sketch of an unusual premise and a possible plot-hook.

Hathalfar holds the writhing troll down with his gloved fist and sword. The beast squirms at the touch of metal. 'How far is Kolm?' he demands for the third time. 'I said! A long way away,' replies the troll.

The characters are stranded on an island, where a wizard, corrupted by the powers of the first Blue Book, has been killed by his own magical experiments. They will discover the awful truth that lurks in his subterranean workshop, and a seed of evil will be sown...

In the darkness in the south transept of the Cathedral of Isielles stands the resplendent Clock of Shadows. It tells more than just the time of day...

An icky sideline plot to a forest adventure.

An impressive citadel in the Askharnn mountains. Their prohibitive laws on travel during the Winter months can be a problem for pilgrims and wanderers.

Unknown to anyone, a glamorous ball for the Duke of Erezi will turn into a confusing and chaotic bloodbath.

She has everything: stunningly good looks, sharp brains and oodles of power: she's going to be a Queen. The only drawback is that she doesn't want to be a Queen.

Archaeologists have long wondered about the origins of 'cup and ring-marked stones', the mysterious rocks found on deserted tracts of moorland bearing markings resembling small shallow pits with concentric rings and dating to the Bronze-age.

Carmo keeps a shop in the backstreets of Erezi. It's not often visited, Carmo makes people feel...uneasy. Even the veterans of the Erezi underworld are uncomfortable being alone with Carmo. But they need to buy their traps from somewhere...

The silver necklaces whose inset gems display the status of the wearer.

A dangerous book of maps...

A transcription, beyng the seminal introduction by Mr S J Ponsuler to the theory and praxis of Dracapodemy, the studie of Dragons' migration patterns. This tome ys to be founde in the librarie of Anserne University, alonge with many years of copies of the Dracapodemyst's Almanac not to mention verious othere tomes on the subjecte.

(Another submission I'm transferring over to the main site from the fora).

The Great Gate of Calast is not like other gates. It's got a mind of its own...

The grisly anthropomorphisation of a rockfall...

Language is an essential part of any culture. Culture wouldn't exist without some form of communication, and humans communicate by speaking. But the connection is deeper even than that. The language helps to define the culture which uses it, and is in turn affected by that culture. This dynamic process is what keeps a language 'alive': Latin is a dead language because the culture to which it belonged no longer exists.