[sir_pudding]

In general I think if you want an aspect of your game to be a full board game on its own, and it's an aspect that the scale of GURPS doesn't handle well, then you are usually better off integrating a good specific purpose board game into GURPS than you are trying to expand the scale. If you want a more abstract, or quick approach instead than subsystems like the chase rules in Action, or GURPS Spaceships combat, or GURPS Mass Combat are good places to start, but these are intended as secondary systems that resolve quickly with minimal detail, not as the centerpiece action.