How about a tiny Espionage game which features only a 6x6 square board and a piece set like this:

yyyyyy
yyyyyy
------
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xxxxxx
xxxxxx

1 Base
2 Mines
2 Saboteurs
2 Spies
2 1's
2 2's
1 3 ( or a 5, it does not matter since it should be just the highest level piece)
I do not know if this is te best piece setup, maybe remove a mine in favor for another 1 or 3. The 3 can be captured by a Saboteur. Two moves per turn, no volcanoes. The game should go really fast as there's nowhere to run in this game.

Edit: If this set is used, with spies on B2 and e2 white can move those spies in such way that Black's pieces are revealed inmediantly as they move. That should not be possible, so maybe remove the extra spy as well in favor to another 1 to have a set like this:

1 Base
1-2 Mines
2 Saboteurs
1 Spy
3 1's
2 2's
1-2 3's ( or a 5)

@dAGGER: I like the idea to remove a rank and file to get the armies closer. The idea at IYT is also good to play I think.