That means no.
And today I might add the mine-limit thingy. Or the scoped hunting bow. Or... something else :P
For the mine-limit, try allowing up to the number of mines you desire. And then, when someone puts another AP mine down, the oldest AP mine explodes. Otherwise, if you have AP mines back all the way you came from, and it simply says "You have too many AP mines!", the player is forced to blow up all of them, or go all the way back to blow up his last mine to keep moving forward. If he goes back, it's a waste of time and he'll be attacked, and if he blows them all up, he'll have no defense against the enemies running on his path. If he kept blowing up the AP mine he last put down, he could not have any progress going forward, either.