The Cauldron is a fan-created expansion for the popular (and very good) commercial game, Sentinels of the Multiverse.
Board Games
Root Cellar Board Game
Root Cellar is a free print-and-play board game about stocking up food for the winter.
18Africa Board Game
18Africa is a free print-and-play board game from the 18xx rail game genre.
Retro Tactical WWII Squad Leader Variant Rules
Retro Tactical is a set of free rules for use with the components of Squad Leader, Advanced Squad leader and other, similar board games.
The CIA’s Collectible Card Game
Freedom of Information Act (FOIA) filings have uncovered a collectible card game used by the Central Intelligence Agency to train agents.
Seriously.