i haven’t done mortars since rtcw and i don’t know how much has changed but here goes
its possible to set up multiple mortars each shooting on a different location and use some kind of map with func_user on it to change the locations and if you use a wide enough random angle your going to get the effect that the whole area is being shelled rather than just one mortar hitting the same place
you can make it so that it must be crew operated but only to the extent that someone would have to stand there and push a button to trigger it. also the user would not get any kills they mortars would count as world kills so u might find people get pretty board of it quickly. you could just have someone set the target location and have it fire off automatically
for my more advanced idea now but highly untested and its pretty much all theory. you could attach a target to a invisible non solid script mover then when the mortar fires it will aim for the location of the script mover and again by adding enough random variance you should get the effect that and area is being shelled
the difficulty with this would be moving the script mover in a way that did not follow a set spline path. you could try some crazy move to markers that are north, south, east and west of the mover or just position plenty of markers around the map and instantly mover the mover to one whenever its selected. this second method would probably be easier than trying to make a mortar per location and allow you to have more possible targets
it will be interesting to see how you fit this into the game flow of your map, i got the idea of having various radios though the map and using them to call a single mortar round in with pretty tight accuracy then use the radio to give more north, south etc and until the mortar is right on target then call a heavier strike to destroy a gate or something and allow progression though the map. you could repeat this several times at different combat locations and to focus the game flow you could do things like put the radio in a dangerous position so you need a team backing up the radio operator, you could even make it so the radio must be repaired and can be damaged and even have to be operated by a field ops so the whole team is involved