Aiming and firing a weapon are fundamental actions in most combat games. It's pretty much all you do in first person shooters. Certainly my previous project Realm of the Mad God relied heavily on aiming and shooting. On the other extreme, Gratuitous Space Battles gives you no control at all, over anything!
In my current project at Jetbolt, players have vehicular avatars: tanks and other heavily armed vehicles. Some of the tanks have forward-mounted guns, but other weapons may point to the sides or rear. Some weapons are turreted, rotating a full 360 degrees. Some guns can hit only aerial targets, some can hit only ground-bound enemies, while others can target anything. There are single-target laser beams, area-affect shotgun sprays, delayed-blast mines and more.
Although Jetbolt's MMO has plenty of guns and shooting, players can neither aim nor fire. We are striving for a mouse-only control scheme that lets players operate the game with one hand free. We'd also like the control scheme to scale up to big vehicles with 10, 20 or more guns. Rather than make the player control all of that, we're having the computer do the aiming and firing, while the player concentrates on positioning and orienting the vehicle, bringing the biggest guns and the thickest armor to bear on the situation at hand.
There is risk in this approach: it may not work at all, or it may work but be unappealing to an audience used to aiming and shooting manually. But in some sense we have no choice but to try strange new things. Small indie projects can't compete with big-budget studios on quantity of 3D assets, dialogue voiceover coverage or cut-scene fidelity. Innovation is the only viable strategy for a small team in a field dominated by giants. So I hope it will work!