Well, since v2.0 you can't do damage through the floor/walls with the rocket launcher, mortar, hagar or electro anymore. I heavily dislike this, but fortunately this is configurable by the cvar "g_throughfloor"
I would really appreciate it to have this feature in the Nexuiz 1on1 ladder. Vote Yes if you want damage through the floor back, vote no if you think this is not needed.