As a teen I tried playing the odd (e.g. WWII-based) Avalon-Hill
board-wargame with my brother, though I found it hard to keep track of all
the rules, board hexes and pieces. Based on looking at the link given, The
Battle of Macysburg doesn't appear quite as highly complex by comparison,
based on my vague memories of playing board-wargames in the 1970s, which
may be a plus for many wargamers that could take it up. Even in the 1970s I
was a serious chess player, and had always liked that the rules of chess
were not overly complicated. That's besides liking the beauty of a chess
set as a child.

Fwiw, I fairly recently came up with 12 criteria I would like personally
for chess variants or other board games of skill; being a chess player, my
criteria were designed to favour chess-like games, and hopefully ones that
could still prove popular. I also hope one day for a chess variant to
replace chess as the new standard version of it, hopefully for at least
many decades, if not centuries, as strong computer engines may diminish
strongly skilled human players in the eyes of at least some of the public,
and also such engines make cheating more possible than before. 

To me personally, the minimum criteria to make for a chess variant would be
my final criteria in the list further below, namely:

"12. Kings that can be checkmated are included."

For me, this could include games that have one (or more) "king" per side,
or games where there are other ways to win besides administering a final
checkmate. This would certainly exclude Arimaa, or Go (which unlike Arimaa
is not listed on the present chess variant website afaik); I've play the
odd game of Go, but not yet any games of Arimaa.

Here are the 12 criteria for chess variants or other board games of skill
that I mentioned; I would note that as of nowadays satisfying all 12 of
them (including computer resistance) may prove to be impossible in the long
run, however:

1. Arguably resistant to computer playing engines (ideally even against
human players that aren't close to being the world's best);
2. Any endgame stage not in significant danger of being compromised e.g.
due to tablebases (adjournments feasible if desired);
3. Significant popularity in North America and elsewhere (ideally played in
clubs and cash prize tournaments);
4. Extensively tested (ideally for centuries);
5. Rules arguably not way too complex or simple;
6. Has significant literature and cultural history (ideally no licensing or
copyright requirements on the game itself);
7. Fixed start position, ideally nice & not same as chess if variant (or at
least empty board, before 1st player moves);
8. Opening phase not in danger of being arguably played out any time soon;
9. Two player game (normally, at least);
10. Not way too many/few pieces or board squares/cells/points, and played
on one board;
11. Pieces look & move nicely & board can be on coffeetable (ideally fixed
start position not same as chess if variant);
12. Kings that can be checkmated are included.

Below is a link to one variant I invented that might be somewhat computer
resistant, and yet still satisfy all 12 criteria I gave to at least some
degree. What I imagined are its main weaknesses include that an average
game may take over 200 ply if reasonably well played (though an average Go
game takes about 150 ply, and Go claims to be a war rather than a battle,
unlike chess), and once a lot of pieces might have been exchanged then the
resulting position might not be very computer resistant (though it may not
matter if one side already stands better or is clearly drawing the game):

http://www.chessvariants.com/index/msdisplay.php?itemid=MSsacchess