In order to incite some discussion in regards to story material, here's the fluff I've written for all of the human weapons back in pre-alpha. Feel free to tell me if any of my ideas suck, or if things should be changed. I'm always open to altering things or incorporating new material.
Also, note that some of this stuff is hilariously outdated, and that I likely missed out changes that are now present in current models. Correct me where I'm wrong.
A common sight among all members of the human military, from combat engineers to high-ranking officers, the single-shot blaster pistol is typically drawn from its holster in only in the most dire of circumstances. When power fails and the more potent weapons run out of ammunition, the blaster is always present for one last heroic charge or final stand. While the survival rate against multiple opponents is abysmally low, the possibility of taking out at least one injured alien with a few well-aimed shots is more than enough to justify continued production of the dirt-cheap weapon.
Each blaster draws power from multiple sources, ensuring that it can operate in a variety of environments. To recharge its internal battery, the pistol can absorb faint emissions of energy from a distant reactor, solar power from sunlight, and even thermal energy from open flame. Between shots, the battery charges a multitude of capacitors along the barrel of the gun, which release a short burst of energy after the trigger is pulled. Although each shot is potent in comparison to bullets, the recharging takes far too long to be useful in combat, and the energy burst travels too slowly to be accurate against quickly moving targets at anything more than point blank range. Even so, it is still considered better than nothing.
The frontier bases of humanity require the repetitive tasks of maintenance and construction, both of which are performed by the reliable construction kit. No actual building is performed by the kit itself, which instead is used to provide a teleportation beacon to offsite warehouses and manufacturing facilities located in non-combat zones. When the combat engineer chooses a structure from a holographic menu projected on the left side of the kit, the selected building materializes rapidly at the designated coordinates: first as a frame, and then the internal components. Two projectors mounted on either side of the kit display an image of the chosen structure, allowing the constructor to make informed decisions on its placement, such as whether it would physically fit or not. Each kit is powered by its own internal battery, allowing it to function even when the main base has been destroyed, a critical feature that allows the survivors of an alien attack to rebuild their infrastructure in another location, given a few minutes of safety.
Damaged structures may be repaired by the construction kit, which houses a small number of nanomachines; these may be regenerated by feeding in metals from the surroundings. Two small sensors mounted above the projector arms survey the state of the building in question, determining which components require repairing before ejecting a spray of the nanomachines onto the location. When the damage is repaired, the sensors examine the structure once again, continuing the nanomachine spray only if necessary, in order to conserve them. While slow, this process ensures that nothing is wasted, a crucial survival measure in the hostile environments the kit often sees action in.
Having undergone relatively few design changes over the last century, the rifle is exceedingly cheap to manufacture, and is thus the weapon entrusted to the newest of recruits. With few moving parts and simplistic circuitry, they are easy to maintain and are unlikely to jam when needed most, making them reliable and a favorite of those that come to depend on its stability during combat. Just as historic rifles propelled a round down a rifled barrel, these weapons operate off the same principle, although with a rapid, magnetically-assisted feed system that allows for an incredible rate of fire while the trigger is held. A small display on the side of the rifle indicates how many rounds are left in the clip, eliminating any guesswork regarding appropriate times to duck into cover and reload.
By far the most common weapon in the human military, it is highly effective against the smaller forms of aliens, with the ability to dispatch most of them in a few seconds of well-aimed fire. As the weapon is configured to fire in bursts over a short distance, it is considerably less useful at ranges, where the highly accurate energy weapons are more appropriate.
Of all weapons in the human arsenal, the painsaw stands out as the most peculiar, for two reasons. The first is that the weapon does not have the same reach as any of the others, in fact working over extremely short distances, which result in considerable risk to the wielder. Secondly, the weapon does not possess a military origin, but is in fact a weaponized form of a common cutting implement used in construction and the processing of highly strengthened metal alloys. Two electrodes jut out from the handle of the weapon, each fed by a pair of miniaturized generators that can give off a considerable amount of power for their size. When a trigger in the handle is held down, current flows between the electrodes, with enough voltage to ionize the surrounding air into searing plasma. If the “blade” of the weapon does not make contact with another surface, such as the body of an alien, the current is cycled back into the generators, with relatively little loss of energy. This, along with efficient power storage, allows for the weapon to be used almost indefinitely.
The weapon is a common sight among starship crewmen, who favor it over the standard rifle for its inability to damage the ship’s infrastructure with stray rounds. Smaller aliens are butchered in a matter of seconds, making the painsaw an excellent choice for those that choose to venture into the poorly lit ventilation systems where they lurk. Even the largest aliens may be slaughtered by several humans wielding painsaws, although at such close ranges, going in without the protection of armor or teammates would be suicidal.
Designed with boarding actions and close combat in mind, the shotgun is a powerful weapon at point blank ranges, where its spray of pellets can tear through alien flesh in an instant. Each shell contains a number of lightweight pellets, which disperse upon firing to cover a larger area than a single bullet can. An automatic reloading system expels the used shells and quickly loads a new one from the clip, although a manual pump is mounted under the barrel in case the gun’s circuitry fails in any way, adding a level of redundancy. As the shells have a greater bulk than the ammunition used in other human weapons and must be discharged after use, there is an increased delay between shots.
Naturally, the shotgun’s pellet spray disperses significantly at more than several meters, making the weapon near-useless at greater distances. It is within that short distance that the weapon shines, being able to take down the lower alien forms in just one or two shots. The spray aids in hitting larger aliens, although the wielder must be careful to time each shot, allowing a few moments to dodge before the next shell can be fired.
Fulfilling a similar role to the more common rifle, the lasgun possesses several advantages of its own. Unlike its bullet-churning cousin, the weapon possesses a single large power cell, eliminating the need to reload and allowing its user to keep a constant rate of fire for as long as the cell is charged and the trigger is held. Each “shot” is a pinpoint accurate, coherent burst of high frequency electromagnetic radiation, invisible to human eyes but readily felt as a sudden shock of intense heat that burns flesh with ease. The amplifier must be cooled down between shots, and while this is accomplished in a fraction of a second, there is still an easily noticed delay in comparison to the rifle.
Although superior to the rifle in most regards, the lasgun’s components are far more expensive to manufacture, and thus it is typically entrusted to soldiers that show some degree of marksmanship and survivability above that of a new recruit. It may be connected to a battery pack, providing even more energy to the power cell. Although eclipsed by the other energy weapons in terms of damage output, it is highly regarded as the most efficient weapon in the human arsenal.