Here are my two favorite camping activities (aside from making s’ mores of course):

Telling tales - On your campout invitation, ask everyone to come prepared with their favorite ghost story. Once the sun goes down, have the kids join you around the campfire. Pass a flashlight to each guest when it is his/her turn. The kids will love holding it under their chin or flashing it in the bushes for effect while telling their ghoulish tale!

Firefly hunt - Arm each of your guests with a mesh bug habitat (or a Mason jar with holes in the top) and send them into the yard on a firefly hunt. The child who brings back the most fireflies in 15 minutes gets a prize.