Well, TacPack has been around since quite a while, I'm surprised some people from the FS community discovers it only now...
But anyways, for those who didn't know, TacPack is not only made to "blow up stuff". The purpose of this addon is to bring to FSX the military features it was lacking until now. This does not limit to weapons, but also radars and other systems. This is made for all those who were tired of flying military airplanes with the instruments of a Cessna 172.
One of the most impressive features is the FLIR screen which offers, in the virtual cockpit, a real view for the laser targetting, for launching laser-guided bombs (GBUs) or missiles (Mavericks), or even for target identification (like for these Customs planes who inspect the unknown boats).
At the beginning, the TacPack features were only integrated in the VRS Super Hornet, making it the most complete and most realistic fighter jet ever made in the Flight Simulator franchise history. Nowadays, a few other planes appeared with TacPack features. One of the best examples is the fantastic freeware F-14 Tomcat made by Dino Cattaneo. Another good example, from the payware side, is the excellent A-10 Warthog made by IRIS.
The civil pilots don't have to fear, as only TacPack compatible planes will be affected by the TacPack weapons. So no, a TacPack pilot will not be able to shoot you down in a multiplayer session.
The AI planes can be shot down anytime, though, and the TacPack also allows you to spot a drone target plane anywhere to shoot it.
Finally, TacPack works only with FSX. But VRS announced recently that they started the developpment of a new version made for P3D, finally
