If you're really determined to get them to play outside, you might want to take it slow. Start with sitting them on an open windowsill so they can get used to the smells/sights of outdoors without actually
being outdoors. Stay with them, so they have a safe place to be, and maybe grab a toy from their cage so they have something familiar, too. Then take them outside without any signs of trying to set them down. Eventually, they may want to get down and play. If, on the other hand, they continue to be terrified, it may just be that they smell a predator (neighborhood cat or racoon maybe), and feel it wouldn't be safe. In which case, they will probably never want to go outside, and you may have to just be happy with a digging box.
