Boys and turning sticks/toys into weapons

I have an 18 month old boy, and 7 month old twin boys.  The toddler is sweet and such a boy.  Loves kitties, cows, mud, rocks, and sticks.  Only lately he's been chasing me down with sticks, and sometimes toys that are long (firetruck's ladder) and hitting me with them.  It hurts.  I've tried screeching and acting all hurt the way he does when he gets hurt, he laughed.  I tried yelling, he laughed.  I tried calmly saying no that hurts, throwing the stick away, and still he laughs.  He's not doing it to be mean, it's a huge game to him.  He grins and runs after me with his "sword".  Sadly, the trees and van have also been targets, but luckily for them, they don't get bruised.  Even his beloved e-te (kitty) has gotten a smack or two.  I even tried smacking him with his own stick, although it was a lot lighter than his smacks, and again he just laughed.

Right now it's a big game for him, but I don't want him to hit when he's mad.  Plus I want him to stop before he hits his brothers or another kid.  What is fun now can really hurt someone.  If he's outside by himself with me watching from the window, he's smacking away at anything with his darn sticks.  And believe me, he'll make a sword out of anything, it's amazing what that boy can find.