The Purple Portal
This is treated as training grounds for new adventurers and players new to OSE. Used to catch up new PCs joining a more advanced party, hone adventuring skills, as a break from a campaign, or when you need a very short game session.

Old School Occult
This work presents four pursuits for individual character development: Alchemy, Herbalism, Cults, and Curses. These pursuits cost gold over week-long abstractions of downtime between adventures. Learning something like herbalism during downtime is not new, but the Time Studying system for expanding such a skill is the main feature of this book. This system allows adventurers to gain benefits that increase with study over time. Who knows, this might even become its own system…maybe.

[RPG] EXperience Series (OSE EXperience, Shadowdark EXperience, etc.)
These are intro adventures designed to highlight game features in under 3 hours. They’re carefully crafted to replicate aspects of character creation, exploration, combat, etc. so players get a snapshot of the full system.