"Tropical lazor beams..."
At last, a decent letter for a sci-fi gaming topic. Today, kids, we're going to be talking about laser guns. Lasers are the classic raygun, a staple of pulp sci-fi and space opera. The Star Trek phaser was originally imagined as a kind of laser as well (it was supposed to stand for "photon maser", i.e. a beam of photons instead of microwaves... except, that's what a laser is already, so they had to retcon "phaser" to mean "phased particle beam"; more on that later).
Blaster weapons in Star Wars are often casually thought of as laser weapons, but of course the nerdy among us are quick to point out that you wouldn't see a coherent "blot" coming from a laser weapon, not if the energy weapon is actually firing light, which moves much too fast to see. Maybe you could see a sustained laser beam, under the right conditions, but never a bolt (or a blade, for that matter). This means that blaster bolts and lightsaber blades have to be plasma, not laser-light. The same is doubtlessly true of most other flashy energy weapons that fire a bolt (like the Goa'uld staff weapon or the Peacekeeper pulse pistol). Energy weapons in the Terminator universe are explicitly known as plasma rifles. On the other hand, in classic Battlestar Galactica, energy weapons were consistently called "lasers", and you couldn't see a beam coming out of the weapon half the time (but that just might've been the cheap special effects). Plasma blasts just seem to be much more scientifically plausible than laser beams, for all kinds of reasons (a real laser has to be focused on its target for quite a while before it will burn through anything; a high-energy plasma, meanwhile, can actually be "shaped" by a magnetic field).
In the space opera campaign I'm running now, normal firearms (i.e. bullets and gunpowder) are the commonest weapons. In sci-fi, these kinds of weapons are usually called "slug-throwers" to distinguish them from energy weapons. The fact that only "slug-throwers" are normally available on the Borderlands worlds should hopefully reinforce the "space western" feeling of the early part of the game. But as the characters move to other areas, whether back into Known Space our out into the Unexplored Reaches, they'll have the chance to acquire more powerful weapons: plasma, phased particle, and molecular disruptor weapons.
A "plasma gun" is your basic Star Wars blaster. It fires a bolt of highly ionized gas, hot enough to burn a hole in someone who gets shot with it. A "phased particle gun" is based on the Star Trek phaser (and the Asgard PPC weapon from Stargate). The principle behind it is treknobabble at its best: imagine a beam of plasma, but somehow shifted slightly "out of quantum phase", so that the ions in the beam don't just strike the first atoms they encounter. Instead, some of the particles actually pass through solid matter, while some do impact. The result is a beam with some really impressive penetrating power, nasty enough to punch a hole right through just about anything (like, say, the hull of a starship). Finally we have the disruptor gun, another staple of sci-fi (including Star Trek; another inspiration would be the gluon gun from Half-Life). This is the sort of weapon that actually disrupts the "strong nuclear force" (carried by gluon particles) that holds together atomic nuclei. Matter so affected is more than just vaporized; it's reduced to sub-atomic particles. Disintegrated. (And not the in sense of Duck Dodgers' disintegrating pistol!)
In game-mechanical terms, these three categories of weapons are simply expressed as +1, +2, and +3 weapons (the last category being the highest possible bonus for an item in the Retro Phaze RPG). In other words, a plasma pistol is about as rare in the Primus Galaxy setting as a mythrill weapon in a fantasy world. A phaser is about as rare as any magical sword with a name and a special purpose. And a disruptor is a one-of-a-kind item, a legendary and unique object (like Excalibur).
"Winona has been very reliable. It's not her fault she jammed."