Trierarch is a set of free wargames rules for naval warfare in the classical era. The game is based on DBA, with measurements expressed as “ship lengths.”
Island Mayhem are a set of free wargames rules for pirates.
This video shows a neat build of a ruined tower terrain piece for your wargames table. It would work well for all sorts of genres and periods.
Elf Fire I’ve Stood On A Dwarf is a set of homegrown fantasy rules.