It depends on how complex you want it to be. One of the simpler ways would be to use a direction and when a hit happens to reverse it. This requires you to check hit in the direction you're moving. All hitTestObject does is check if the objects are overlapping. It's best to use direction instead for something like this. For each wall you need the objects to be separate. Your best bet is to place each wall object into an array to cycle through. There are quite a few tutorials out for this already. What version of actionscript are you using?