Thermopylae is a free print and play wargame about the classical era battle between Greeks and Persians.
From Impact Games, Elfball is a set of fantasy “football” rules. It’s played on an oval field, so it’s not like “American Rules.”
MS Era is a set of free wargames rules for playing with those Mobile Suit Gundam figurines.
Mini Rogue is a free print and play card game “profoundly inspired by roguelikes and roleplaying games. ” The entire game is on nine cards, so there’s a minimal amount of printing.
Plastic Brigade is a set of fun rules for dollar store toy soldiers.