A shooting solution is not for wargames. For instance, on a submarine, when the weapons officer announces "I have a shooting solution!", it means that the sonar, computers and wepons have linked up and have determined the range to target, depth of target (if it is another submarine), water temperature, the firing submarine's depth, and has calculated the projected run time for the weapon (in this case, a Mk48 wire guided torpedo).
The down and dirty:
A shooting solution means that we have done the math and are ready to fire.