Here's one for a future HIghpoint game.
A forward observer is in position somewhere near the town. Team X in in town and Team Y is awaiting the finish of the artillery barrage to attack.
A co-ordinator (like Spaz did the other day) takes the info from the hidden observer and tells people which buildings/areas are getting hit. Once the shells start falling, team X can begin the hunt for the observer. He (the FO) can move if he feels he's trouble. He is permitted anywhere within visual range of town. He must be able to see what he directs fire to. Anyone in a called out building is dead. If the FO calls for fire on troops in the open, and they haven't moved within one minute, they too are called out by the co-ordinator.
The FO will have a grid map as will the co-ordinator. The FO gives the co-ordinator his target on the map and the co-ordinator makes the calls. As long as the FO remains at large, he can call fire in on the town. Once his side's troops are in town, he can take fire missions from squad leaders.
There is a time to target of 2 minutes. That means that from the time the FO tells the co-ordinator his target until the co-ordinator calls the target out or destroyed, there is a two-minute lag. Obviously, someone might either get lucky and leave the area before a shell lands, or walk into a target (just like in real life).
After 15 minutes have passed, team Y must press their ground assault.