Rocket Launcher

The Rocket Launcher (or RL, as it's known) is a weapon that has appeared in various incarnations in all of the Unreal games. Its behavior has remained fairly static: primary fire fires a single rocket, and secondary takes more time to load up before releasing multiple rockets. In all versions, the Rocket Launcher can "lock on" to targets if the crosshairs hover above a target for a brief amount of time. If the RL is locked on, rockets' paths will curve to try to intercept a moving target. However, this is relatively easily dodged and the target lock is easily broken if the crosshairs move away from the target before firing.

Unreal
See 8ball Launcher Fires a single rocket or multiple rockets if the fire button is held down. Fires a single grenade or multiple grenades of the alt-fire button is held down.
 * Primary Fire
 * Secondary Fire
 * Ammo
 * Damage

RTNP
Same as the Unreal Rocket Launcher, only this time around it's actually called a Rocket Launcher.

Unreal 2
A.K.A. Shark. Behaves the same as the Unreal/Unreal:RTNP Rocket Launcher, with slightly different timing.

Unreal Championship

 * Primary Fire
 * Secondary Fire
 * Ammo
 * Damage

Unreal Championship 2
Fires a single rocket. Charges up to three rockets, each of which can split in two if activated in midair.
 * Primary Fire
 * Secondary Fire
 * Ammo
 * Damage

Unreal Tournament
Fires up to 6 rockets at a time, released in a horizontal line formation or, by pressing alternate fire while loading, in a tight cluster. If you hold tour crosshair on a target long enough (assuming your target is not far away) you will hear beeping sound (your target will hear it as well) and crosshair will take a form of little red cross in a circle. This signifies enable of a lock-on feature. If you fire your rocket at this time it will try to follow your target. Generally speaking lock-on is pretty weak and anyone can escape it by strafing. Fires up to 6 grenades at a time. Grenades bounce from obstacles and explode after a certain amount of time or on contact with player. Upon pick up Rocket Launcher will contain 6 rockets, maximum ammo capacity being 48. Default ammo pack has 12 rockets in it. Direct hit by rocket or grenade delivers 112 damage to a target.
 * Primary Fire
 * Secondary Fire
 * Ammo
 * Damage

Unreal Tournament 2003 and UT2004
Fires a single rocket. Fires three rockets in a horizontal line, and, by pressing primary fire while loading, can shoot up to three rockets in a tight spiral. Rocket Launchers have 12 rockets when they are picked up, and they can hold a maximum of 30. Rocket Launcher Ammo Packs hold 9 rockets each. It takes a bit under 1 second to load a rocket.
 * Primary Fire
 * Secondary Fire
 * Ammo
 * Damage

Unreal Tournament 3
The UT3 Rocket Launcher is reportedly about the same as that of UT2003/4, possibly without the capability to shoot only two rockets in a spiral.

Tactical Use
The Rocket Launcher's rockets fly straight, do a lot of damage in a direct hit, and have a fair-sized splash damage radius. (Because of the splash damage, Rocket Launchers are less than ideal for close-range fighting and are notorious for causing suicides in this situation.)

Since Rocket Launchers are the most powerful standard weapon except a sniper and they have a reasonably fast reload rate and a large splash damage radius (hence the RL is called a "spammy" weapon), they are a favorite of new players. Because it's much more rarely used by advanced players, the Rocket Launcher is often found opposite the Flak Cannon in Capture the Flag, Double Domination, and Bombing Run maps, and in either wide-open or very tight places in Deathmatch or Domination. The theory behind the latter locations is that a weapon is most balanced if it is placed in a location where it is least useful; since the RL is usually considered a mid-range weapon, these locations make sense.

(The following ideas (but not the text) are mostly copied from UnrealWiki)

Use in Onslaught (UT2004 only)

 * Rockets have a lot of momentum, so they will temporarily stop or slow down Scorpions and usually change their direction slightly, disorienting the driver. Three rockets kills a scorpion.
 * Since Rocket Launchers are the second-most-powerful weapon against vehicles (factoring in their rate of fire) they are the most useful weapon to combat Goliath tanks and other large, slow vehicles (not including the Hellbender unless it's coming straight at you) after AVRiLs. However, Mantas and Raptors are usually too agile to be hit by rockets.
 * Because rockets fly very straight and cannot be shot down, they are ideal for shooting Power Nodes from a distance. A useful tactic if you're bad at aiming is to line up using the Lightning Gun or Sniper Rifle and then switch to the RL without moving.

Use in Deathmatch and other Gametypes

 * Loading up on rockets before bursting in to an area where you know there are enemy players allows you to unleash a powerful attack on multiple enemies before they know what's going on.
 * Players in the damage radius of a Rocket are lifted off the floor, preventing them from jumping or dodging. Good players can predict the landing spot and send another rocket there to greet the enemy.  This ability can also be used to boost players themselves, although the Impact Hammer (in UT) and Shield Gun (in UT2003/4) usually take this role.
 * Hitting the ground near a player's feet is easier than hitting a player because, well, it's a larger target and it's not moving. Often the splash damage is plenty to hurt the enemy.  Jumping in the air gives an easier angle from which to aim at a player's feet.