Since Brandywine is a simple fast playing wargame with a small number of units, how is it so endlessly re-playable? Is it? If so, why? Well, let me tell you IMHO what makes this game so great.
First off, all other things aside, it plays quickly for a wargame. I played a game last night and took pictures and kept notes to blog about it, and I finished in under 30 minutes! Admit it, no one wants to spend 4+ hours LOSING a game. If you lose, for whatever reason, double down and go for best of three! With Pub Battles; Brandywine you will have the time.
Secondly, this is a wargame that you will spend more time playing than looking up rules. This is a game that after the first 2 or 3 games you will rarely, if ever, look at the rules again. This is not because it is so Yahtzee simple, it is because the rules are intuitive. There really aren't any gamey ways to rules-win this thing.
But the real secret to this game's never ending fascination and re-playability is the positive synergy that the admixture of turn order and rules of engagement coalesce into, creating an ever changing kaleidoscope of opportunities and twists of fate. Here is the critical mechanic to understand, you can move even if an enemy unit moved adjacent to you! There are no locking zones-of-control. This means that if your command is not picked to move earlier than your opponent, or if you are able to delay your command's movement, you can choose which battles to fight (or if you are trying to capture some critical real estate, you can try to move before your opponent).
Of course, at first blush this seems too good to be true. A unit just walking away from combat at its convenience. Well, that's not really what is happening in a Pub Battles game. Rather than thinking of it in a linear "I move/They move" sense, it is important to think of it in the relational terms of "those units started in those positions in those conditions and after an hour and a half they were in these positons in these conditions."
Pub Battles accepts that there is no way, no detail of simulation, that can cover all the eventualities of combat. For every rule that simulates a certain event or condition, there are countless similar events and conditions that can't be simulated because the rulebooks and the players that must read them can only cover and retain so much. Better to design for effect. If two units meet in combat they will fight until one or the other retreats in disorder or is eliminated, sometimes both retreat in disorder simulating combat to exhaustion without anybody getting the upper hand. As a General at the command post, that is all the information you need and are given.
The end result is a quick and fun game that is endlessly re-playable.