Similar in spirit to the late, lamented Space:1889 cloudships rules, Aeronef is about Victorian era armored flying gunships. There are some outstanding ships’ logs for the game here.
rules
Blood Bowl Soccer
Blood Bowl is one of Games Workshop’s smaller games, but its been around for as long as I can remember. Here’s a Bloodbowl variant that uses the game to play European "Football" — soccer.
Ancient Battlefields
Ancient Battlefields is a set of free wargames rules "with an emphasis on Command and Control". The game is over when the opposing general flees the field.
Caliburn’s Wrath Arthurian Rules
Caliburn’s Wrath is a set of free wargames rules from Matt Cappetta for the Arthurian period. The rulesCaliburn’s Wrath are “intended to represent intense clashes between small bands of foot soldiers.”
Starship Troopers For Dirtside
Here are some rules for using the Dirtside II system to recreate battles from Heinlein’s Starship Troopers.