The best Civil War wargames were published by SSI in the distant
past and grouped together as _The Great Battles of the Civil War_ series
(some of these were later rereleased by the TSR game co.). These were board
games at the regimental level and were extremely detailed and bulky to use
(high piece-density on the board, large maps), though immensely enjoyable.
I don't know how readily available they are now, but here are a few of
the games:
A Gleam of Bayonets: Antietam
Terrible Swift Sword: Gettysburg
(these would be the easiest to find)
also: A Wilson's Creek game
A Monococy Game
(I forget the titles to these)
and there are others.
As for computer wargames, I have not seen any good tactical
battle simulations. I would love to hear if there are any available for
the Mac.
Frank McDonnell
fmcdonne@reed.edu