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A minimalist d10 roleplaying core.

A d20-based rules engine... from 2005.

An SRD for creating Breathless games.

An SRD to make action packed RPGs with forward momentum.

VEN6 is a roleplaying system designed to create narrative storytelling games with conflict mechanics and a GM option.

An Introductory TTRPG Design SRD

A setting agnostic Cooperative Storytelling Game + SRD

Little systems for TTRPG designers

Universal guide for minimalist, FKR-style games.

System Reference Document for the Four Points RPG System

The open-source basic rules of the 4C System / Four Color System

Vis-a-Vis is a fast, modular, and competitive RPG system focused on player vs. player interaction.

Build action packed, illuminated RPGs

An SRD for one page solo TTRPGs.

A System Reference Document dedicated for hackers and game designers, in order to create game by Following the LEADS.

An SRD for creating DELVE expansions

An minimal OSR adjacent system laid out as equations.

A Toolkit For Creating Single-player Exploration Games

A Systems Reference Document for Beak, Feather, & Bone

A primer for amateur designers to make their first Blades in the Dark hack

a d4-based RPG microsystem

Multi-genre Engine for Ludicrous Diversions (RPG)

v1.0 System Reference

A dark mystery horror investigation TRPG

A Supplemental RPG System by Nathan Mehlhorn

A tabletop RPG

Generic Immediate System for Tabletop