Okay, in this conversation which has rambled over a few different threads
now, you mentioned my 12x16s. I've done, basically, 3 different games that
are different kinds of games. One came out quite good, and spawned larger
[and smaller] variants. One is fascinating, but is more potential than
finished game at this point, and that potential hints at different kinds of
chess games. The third is a bust, one of my biggest flops, ranking right up
there with goChess as a game that looks so good in theory and so bad in
practice. That would be SpaceWar, a game in the Games Garage [as is
goChess], and deservedly so.*

All three games have 3 major things in common: first, they all have 32
pieces/side, and second, can be played face to face using 2 standard chess
sets. For some games, the pieces may need to be marked with colored twist
ties, unless the players have several colored sets. Third, they are all
multi-movers. The one major difference between SpaceWar and the other games
is that SpaceWar is the only one that does not use leaders of some sort.

So for starters, the density is 33%. This is enough to speed up the game
all by itself; you don't have so many pieces to wade through, compared to
the 48 pieces per side with the 50% rule. But the major difference is the
piece-type density: it's 5 with the most successful of the 3 games,
Chieftain. Not even close to 19. [I do go up to 7 piece-types on the 15x30
version, but that's a board with 450 squares.] 

The Chieftain games all tend to be decided, if not done, within 40 turns,
partly because they are multi-move. However, the pieces only move 1 to 3 or
4 squares maximum per turn, so this is obviously not the full answer. The
other half of the equation is moves per pieces per turn. To illustrate: in
FIDE chess, there are 16 pieces to start, and the players move 1 piece per
turn, 1/16th of their army, or just over 6% of that army each turn. This
percentage increases steadily as pieces are lost, but the first loss takes
you down to moving 1/15th of the army, the next, to 1/14th, or about 7%. By
the time you're through the opening and into midgame, you might have lost
6 pieces, so you are moving 1/10th, or 10% of your army. When you've got
your king and only 4 other pieces left, you're moving 1/5th, or 20%, of
your army. This is not a very high number. 

Let's look at Chieftain [effectively all versions from the largest to the
smallest]. At start, 1 in 8 pieces is a leader. So, 1/8th of your army is
moving each turn, or 12.5% That's a high number to start with. You move 4
pieces/turn, and your entire army of 32 pieces can be moved in 8 turns. And
the mechanics of the game are such that players tend to trade 2 or more
pieces/turn, when actively fighting each other. After 5 turns of combat, at
2 pieces lost/turn, your 32 piece army has shrunk to 22 pieces, but you are
[most likely] still moving 4 pieces/turn [or you are losing.] This is
roughly 18% of your army per turn, in early midgame, and it only goes up as
the game progresses. The pace of the game is twice as fast as a standard
chess game. Basically, in midgame, you can move your entire army every 4-5
turns. This gives a bit of a different character to the game, because the
individual units are very slow, but the army is very fast. I think this is
the effect that allows Chieftain games to finish in less turns [but not
fewer individual piece moves, which are 2-4 times as numerous in
Chieftain.] These games emphasize the wargame aspects of chess.

The concept with fascinating potential is the chesimals series of games. A
chesimal is a second-order chesspiece, with a variable footprint. It is
made out of a number of individual chesspieces of various types, that are
required by rule, even though each piece moves individually, to effectively
move as a unit. The 32 pieces per side are assembled into 4 chesimals.
There are, so far, 3 different types of chesimals, each with its own unique
characteristics. I'd originally thought of these higher-level pieces as
like army corps, but in practice, the game feels like a combination of
chess with a wargame touch and Conway's Game of Life, which leaves me
wondering what will evolve out of it. 

There you go, George, my 3 [more or less] 12x16s, complete with critique.
I figure one good, one bad, and one, who knows, maybe 'interesting'. [And
maybe just 'ugly'.]

*SpaceWar has attracted a guest mechanic, John Smith, who was intent on
souping it up quite a bit. The results are in the garage.