[tmcc]

My tcw: I basically agree although the leaky part might be a little messy to implement. One ship, unless it was extremely fast, could not realistically blockade a whole planet so I agree that the effectiveness of a blockade should depend on the size of the force. One simple way to implement this would be to create a "% to blockade number" based on the criteria you list and then making a roll against that number every turn. If the planet passes it's "blockade roll" then resources get through (i.e. no blockade). If the planet fails the roll the it is blockaded that turn.

I think another key attribute of the blockader should be speed. Functional armament and an attack strategy are fine, but if the engines are shot up then the effectiveness of the blockade would go way down. Like wise some assumption needs to be made about the speed of the "invisible" transports that carry those resources back and forth. This speed should be based somehow on engine tech level and would then be compared to the blockader's speed as another factor in the "% to blockade number".