Roar of the Crowd is a set of free rules for playing science fiction, fantasy or historical gladiator games.
Prince August Fantasy Rules is a set of free wargames rules that originally appeared in the 1980s in a Prince August miniatures catalog.
Elfball is a fantasy football game
from Impact Games, a new company which produces fantasy football figures. I’ve always wanted to get into fantasy football, but painting those figures has jsut not been on my short list.
Dark World War is a set of free wargames rules — actually pay what you want — for playing WWI games that include demonic and mythological creatures.
The folk at One Page Rules have released version 2.3 of their Age of Fantasy Generic Rules. The rules have one page (front and back), and there is a vast list of army and faction stats to download as well.