The game has a variable ending. At the end of every defender's turn, the defender rolls a d6. You keep adding the numbers rolled and when the total gets to 21 the game ends. So a game on average will last 6 turns, but it could be longer or shorter.
I think you could probably play it with single figures instead of bases, in 28mm for example. Indeed, I was thinking it would be good for a quirky period like VBCW. Each base represents a squad, more or less, and these are grouped into platoons of 3 bases, with a number of platoons making up a 'unit.' But this doesn't really matter, the game is mainly for combat between semi-organised militias.