Grenades part 2:

This is a video of the latest status. You can throw grenades at a low or high trajectory, which is selected by the fire mode button. The high trajectory setting is good for throwing over objects in the way and low trajectory for throwing further. 

The player initiates the throw by pressing the "throw" button on the HUD, or by holding down the CTRL key and then the ballistic path  is displayed. The player can move the mouse to select the desired path and then press the left mouse button to throw the grenade.

Normally, roofs are removed so the player can easily see inside buildings, but when throwing the roofs are temporarily put back on, to prevent being able to throw through the roof.