Guided missiles start to become common in TL7, and increase in effectiveness, range and cheapness as technology progresses. They are rated according to how 'smart' they are.
The main distinction between missiles and rockets is that the latter lack any means of guidance after launch. A missile is, in theory, able to track its target as it tries to evade. The capability of the guidance system is an important feature of any missile.
In a missiles weapon description, it will be described as Gu(X/n), where X is the type of guidance system, and n is the 'skill' of the system.
Very basic missiles are manually guided, being controlled remotely by an observer (normally the firer) with a simple joystick. The missile has no guidance system of its own. Such a missile always uses the Heavy weapons skill of the controller.
A homing missile locks onto its target using very simple criteria, such as heat signature or noise. Once fired, the target cannot be changed, and they can be confused very easily, by sending out decoys which are brighter/noisier than the target itself.
A smart missile is remote controlled by an observer, or locks onto some targetting signal. It has no intelligence itself, and the observer must maintain control until the last moment.
In some ways they aren't as good as a homing missile, since they aren't fire-and-forget. However, they can lock onto any target, not just those giving out heat or noise, and the human operator is often harder to fool with decoys than a simple homing missile is.
Brilliant missiles are capable of homing in on a designated target. Designation is by a human operator, but after the missile is fired, no further designation is required (unlike for smart missiles). Brilliant missiles may use a number of techniques for recognising the target, but are mostly based on visual or signature recognition.
Clever missiles are capable of making their own choices about targets. Once a target has been selected, they are capable of following that target themselves without outside aid. Note that a clever missile actively recognises its target, it does not rely on a simple criteria such as heat for tracking.
Clever missiles may be fired in the general direction of the enemy, and is capable of choosing a target itself based on a pre-defined profile.
Genius missiles are capable of selecting a target based on many criteria, using strategy to select not only the best target, but also the best route to the target.
The most effective genius missiles are capable of working together in swarms, deciding between themselves how to divide up the targets, and changing targets as conditions change.
Contra-grav genius missiles have the capability to lay in wait for targets, dodge counter measures and generally behave like living attackers.
Guided missiles are treated as missile weapons. They generally have a range increment of 0 (distance to target does not affect accuracy). Self guided missiles (normally clever and genius) use their own skill in an attack.
A missile cannot hit a target at short range. It is within the weapon's arming distance.
At medium range, the missile behaves as normal, attacking with its attack score and doing full damage.
At long range the missile is nearing the end of its capability, and is less able to manouevre to hit the target. It's attack score is halved.