BartimaeusI am write a scenario for the TTRPG Liminal Horror. The system has a pretty good structure to write your own stuff but the community as some really great ressources as well.
I very good is the workshop for the classic jam, either watch the entire workshops or just the presentation is enough to push you in the direction to create some stuff: https://liminalhorrorrpg.com/seminars/#adapting-a-mystery-liminal-horror-writing-seminar