Chaoclypse
Teen (13+)
While it is meant for OD&D and its retroclones (such as Delving Deeper or White Box: FMAG), everything within is easily compatible with most OSR systems, such as B/X or OSE.
The zine is compact enough to home-print, but also filled to the brim with useful tables and procedures!
SOLUS includes:
Yes/No Oracle
Situational and Descriptor Oracles
Detailed but swift dungeon generation
2 methods of treasure generation
Backgrounds
Optional Heroic Rules
* Guidance on handling reactions, traps and death solo