The missile launcher is a powerful weapon which fires slow-moving missiles that explode on contact with enemies. The missile launcher's explosions are more potent than those of the grenade launcher but the projectiles themselves move at a slow pace and firing speed is also fairly slow, allowing zombies to easily run around missiles or miss in general. As such, missiles become more useful against stationary bosses and large hordes of monsters; dodging or circling around enemies requires better prediction of a monster's movement on the player's part when firing to compensate for the missile's slow speed.
On upgrading, the missile launchers gains faster projectiles, increased damage, increased firing speed, larger explosions, and homing capabilities.
Just a little change to the barrel and the larger version of the rockets fits in it, too. These accelerate faster and also do more damage.
A few new parts and a touch of oil works wonders here. A quicker rate of fire and an improved speed increase my chance to actually hit the target that I aimed for.
If I carefully unfasten the head of the missile, I can attach a new head which contains 20% more explosives. The heads also contain a control chip that allows slight corrections to the flight path.
A weapon on the brink of unmanned space travel! Another 20% improved detonation power upon contact and heavily improved steering capabilities. You can lay waste to whole areas with it now and even follow the horde as it moves.