creating a custom explosion destruction effect.

[Billo]

what i need is : do you know when you cap the last point on badwater and it explodes and then things fall from the sky? like barrels. i want to make something similar, how can do that?
and lastly i would like to know how to add a picture on my map when you join the map.
like when you join badwater it shows you 2 pics of the map.

 

[Pocket]

They used a physics simulator to create an animation of the explosion, and exported the whole thing as a single animated prop. Same thing they did for the collapsing bridge in Half-Life 2 Episode Two and the opening sequence in Portal 2. It's not something you can do in-engine.