Black Mesa Crossbow

The Crossbow is a long range sniper weapon featured in Half-Life. It is extremely effective against distant targets, but is difficult to utilize in melees or against fast moving opponents due to its very slow reload and the low velocity of the shot. The primary trigger fires a bolt; the secondary trigger zooms in on targets.

Construction
In Half-Life, the Crossbow is first acquired during the chapter Apprehension, where it must be used to kill an Ichthyosaur. It seems to be modeled upon modern composite bows. Its ammo consists of five feathered darts in a magazine. These are fed one at a time into the main mechanism, which utilizes a high-tension wire to launch the dart. A scope fixed on top allows the user to zoom in on his or her target. Once fired, the wire must be pulled back manually and the device reset with a new dart; thus its long reloading time.

Employment
It seems the Crossbow was used only for unique tasks such as these at Black Mesa; ammo for it is scarce, and neither soldiers nor security guards are ever seen using one.

Though a scientist refers to it as a "tranquilizer gun", the darts definitely kill their targets.

Tactical Considerations
The Crossbow is an exceptionally powerful weapon if used correctly, but like every weapon in Half-Life, it has distinct advantages and disadvantages.


 * Once fired, the bolts don't have as much velocity as, say, a bullet, so they are effected by gravity more over long distances and follow a slight downward arc as they travel. Users firing over long distances must account for this drop by aiming slightly above the target.


 * The crossbow is effective against most enemies, but is best saved for tough, slow moving enemies or those unaware of your presence. If attacking marines or Vortigaunts, aim for the head for a one hit kill, even on the hardest skill levels.


 * The crossbow is particularly effective against Ichthyosaurs, since it is both powerful and capable of firing underwater.


 * Once targets start to move in any way except a straight line, using a Crossbow becomes a game of chance. If you plan on using it heavily, practice trying to hit moving targets; you need to aim in front of and slightly above your opponent.  If you think your opponent is using one, get into the habit of zigzagging and generally moving in awkward patterns.  Try spraying their hidey-holes with bullets, or throw grenades; just the sound of the latter is usually enough to make zoom-lensed players panic.


 * Crossbows in close combat result in Mexican standoffs. You can kill an opponent easily if you hit him, but you'll only ever get that one shot.