In Air, Land and Sea from Arcane Wonders, two players battle for control of theatres of operation. It’s a micro game that plays in about 20 minutes and has gotten a lot of good reviews. You can get the free print and play version of Air, Land and Sea at the link.
Babylon is a free print-and-play game about building a Babylonian tower with mosaics, gardens and masonry. It uses the Roll and Write mechanism.
Unconditional Surrender: Case Blue is a free print and play wargame for two players about campaigns in southern Russia from 1942 – 1943.
Farrapos is a free print-and-play boardgame about the 1835 – 1845 revolution in Brazil.
Periplus is a free two player wargame that abstracts a battle between two fleets of ancient greek warships.