Princes of the East is a political / military game for the period immediately following the First Crusade. Like all of the Perfect Captain’s game, this one is professionally done, with some amazing graphics.
Bocage Hedgerows Made Easy
Pijlie’s Wargames blog has a photo tutorial on making a hedgerow.
Broderbund’s Ancient Art of War (1984)
The classic Ancient Art of War game, released by Broderbund in 1984, is available to play on archive.org in an emulator.
Dr. Who Exterminate Rules From Warlord Games
Warlord Games offers its Dr. Who Exterminate rules free for the downloading.
Bombers Over Germany Miniatures Rules
Matt Fritz offers a free set of miniatures rules for playing games involving B17 bomber runs over Germany in World War II. Looks like fun.