These rules have just been updated for 2017. They are hex based, with units being regiments (artillery is a battery) and the rules include two scenarios and design notes. I have used Kallistra 4" hexes and their 12mm ACW figures in my gaming, but hex size, unit size and figure scale are up to the individual to choose.
Rather like my Tiger at Minsk rules, the game runs from a Game Clock, so you get results like 'the unit retreats 1 hex and is disordered for 15 minutes'. As casualties acrue, units will find it harder to pass their capability tests and so become less efficient. At some point casualties levels will cause units to fall back and eventually casualty levels will see units removed from play.