Wall Destruction Animation (Help?)

Im trying to get an animation where my wall model destructs where an object has hit it ( boulder from catapult hitting wall):

i have failed to produce anything good in ‘blender render’ where i would set keyframes using the explode modifier and the particle system,
when i use the “blender game” physics with a ball hitting a wall i got much better results,

http://imageshack.us/a/img208/2009/walllw.jpg

but i need to have the animation in frames to export the damage of the wall as wavefront (obj) files at different frames in the animation.

So my main question is, can I make my animation into frames with blender game physics, or do I have to manually animate each brick separately to achieve an animation with frames?
Any other ways of doing this?

thanks

Look at 20:00 to see similar setup to mine http://www.youtube.com/watch?v=UfXq-aM026Y

For anyone experiencing the same problem as i had, then read the reply i got from other forum:

http://www.blender.org/forum/viewtopic.php?p=99225#99225
"Try setting up your animation for blender game engine. Don’t forget to change to Blender Game Engine from Blender Render. Run the game and get the bugs out until you have it the way you want it. Then in the info bar at the top of the screen, click on the “game” button. In the dropdown menu there is a box next to “Record Animation,” check it. Now run the game engine. This should have recorded every thing that happened in the game to keyframes. Note that this process will record 60 frames a second, I don’t really know how to get it to record slower than that, so just play with the settings. Hope that helps. "