The Battle Game of the Month Blog has the outline of a set of free wargames rules for playing games set in the Russian Civil War. They’re inspired by Joseph Morschauser’s rules.
Return To The River Don is a set of free wargames rules for 15mm miniatures battles set in the Russian Civil War.
Red Army White Guards is a set of free wargames rules for playing battles set in the Russian Civil War. Its played on an offset grid and is apparently designed for 15mm figures; the rules call for three figures on a 30×30 mm base.
Dave Waxtel offers a set of Russian Civil War rules designed for 25mm 28mm games. The rules are very interesting in that they not only have the usual rules for force composition, maneuver and combat, but also provisions for pre game “political maneuvering”. There’s also information on the various forces. I’ve always wanted to do Russian Civil War games, and this one looks pretty good for such adventures.
Red Hordes is a set of free wargames rules for the Russian Vivil War. They’re similar to DBA/DBM.