Weapons, because while I was all set to do one post here a day, sometimes the brain says "screw you and your plans, you might as well write this s**t down because otherwise you'll forget"
In the distant future of 2163 the most common thing people think of when you say weapon is largely the same as what it was 300 years before, a gun that projects its projectile downrange through the combustion of its propellant in a violent reaction. This is because, despite how amazing some of the advances in personal and seige weaponry have been, gun powder actually has a lot to recommend itself with. It's self oxidizing, which means it functions just as well in atmo as it does in vacuum, it doesn't require batteries or any other sort of power supply, and while advances in defense technologies and personal augmentation means that the traditional 9mm hollow point of grandpappy's day no longer strikes fear into the hearts of innocent bystanders, continued advances in the field means that in the world of today gunpowder is still relevant.
With that out of the way, on to why you're really here, to hear about the awesome but slightly less practical weapons.
Electrolaser (picture the shock rifle of Unreal Tournament, which I'm assuming someone over there read about testing in electrolasers and said, "I want THAT in the game")
Definately falling under the exotic label, the electrolaser functions by using a laser to excite the air in a beam to the point where it forms a channel of plasma, which then gets a nice lightning bolt to shot down its length to even out the electrical thingymajigs. Listen, I'm tired and applied awesome is not my major.
Primary uses: anti-personnel/anti-materiel sniper rifle is the image that first pops into peoples minds when talking of elctrolasers, though it isn't the only use. During the war batteries of electrolasers were set up as anti-missile point defense systems, being significantly cheaper and more effective than launching your own missile at the incoming missle. They're also commonly mounted on (attack helicopter/transit helicopter style) gunships. Due to the exotic nature of the weapon, most systems are not properly shielded against sustained fire, and most infantry style troops are infact not shielded against directed lightning.
CONS (in all caps because killing people with lightning is awesome and everyone should want to use one of this, so we need to cover why a generic assault rifle is more often better)
-Due to how the weapon works, it can ONLY be used in an enviroment with atmosphere, and when taking it from one type of atmo to another (say Earth to the outside of a Cytherean hab) on board software needs to be updated so as to provide the proper amount of power to the laser to properly ionize the air. Most vehicle mounted weapons have the processing power to do this automatically, however the man portable version must be updated by hand (newer models generally have the most common loadout preinstalled, just requiring a brief trip into the system menu)
-Power. These things eat power like it's going out of style. This means that one either needs to be plugged into the local power grid, or as is the most common case in the field, plugged into a portable fusion bottle. Said bottle needed to be lugged with you, oftentimes by the spotter in a 2-man team. Just because antigravity exists doesn't mean we can eliminate all weight, and most man-portable fusion bottles already have so many interconnected grav fields that too much outside interference can cause containment failure, with all the fun that the image of a fusion reaction escaping containment brings to your wonderful imaginations.
And speaking of fusion escaping containment, that brings us to our second kind of exotic weaponry...
Plasma Weaponry AKA The Marine's Portable Kitchen
Capable of both opening up passages into opposing ships (aka can opener) and cooking adversaries inside their own power armor (Microwaved Marine) plasma weaponry saw significant use in the latter stages of the war. Because any personal armor capable of standing up to the sort of micrometeorite hits you'll see in a space engagement is more or less impervious to small arms, and boarding squads already carried a plasma lance to open passages into opposing ships (and yes, sometime boarding is called for, you don't always want to just nuke them from over the horizon) plasma weaponry saw significant development.
Heavy, unless if you're wearing power armor, you don't really want to have to try to use this. And, in case you needed another reason to not use this outside of power armor, because more plasma weapons are basically just opening one end of a fusion bottle and letting all the fun stuff shoot out, you also get a nice dose of hard radiation. Oh, and the very slight chance of catastrophic containment failure when you stop firing, which is why marines felt a need to give the weapon a nickname, because it's less scary when you get to walk around with a portable kitchen as opposed to the official moniker of Directed Plasma Lance.
Can't be used in atmo. Though this one is less of a hard and fast rule than the shock rifle's in atmo restriction, it's just that as the amount of atmosphere increases the range of the plasma decreases. At ground level on earth you're basically just holding a really expensive and dangerous blowtorch, and really, there are safer and more efficient ways to do whatever you're trying to do at that point. Why not try Russian Roulette instead if you really have a deathwish?
Functioning along the same general line of thought as gunpowder weapons (and crossbows, bows, and thrown rocks before them), a mass driver exists to propel a piece of ferrous material downrange with as much force as possible. The only reason they're not man portable is because the recoil issues haven't been solved yet, and the power issues, but the moment someone figures out the recoil I'm sure the power issues won't be too far behind. There's money there.
ANYWAY, mass drivers are absolutely amazing at what they do, and they scale beautifully as well. Spinal mounted mass drivers are used on many of the asteroid breakers, with numerous "point defense" drivers to further break up their prey, as well as protect against the stray piece of valuable mineral that might damage the ship. Note that the same general principles work on a war-ship as well, though in that case they'd also have missiles with which to pelt the enemy.
In this case I'm referring to a weapon that fills the same general role as the 40mm grenade launcher, with the added bonus that on-board computers allow for EFF and target-locking functions. Other uses are in ship-to-ship combat where a single large missile will split either shortly before it gets in range of point defenses or when it appears that an anti-missile missile has achieved lock, launching anywhere from 6-600 submunitions with their own onboard tracking and defense avoidance programs. While this method is clearly less explosive on a gram for gram basis than a single missile that uses all that payload for its own explosives, it has the benefit of potentially overloading defending point defense programs with too many targets, allowing more powerful missiles through due to poor target selection.
and I'm sure more weapon ideas will come to me, but that's it for today... I'm pretty sure...
Pulse Rifle (HL2) <-some sort of projectile weapon using exotic method of pushing things downrange.
Glowing Crossbow Bolts (HL2) <- superheated to deal with heavy armor, though I really don't think that'd work...
Shredder Ammo (ME2) <- think of something to do with the name as inspiration
Disrupter Ammo (ME2) <- "--"
M-920 Cain/Littleboy (ME3/FO3) <- because manportable nukes
Mauler (HL3) <- Hand shotgun
Fuel Rod Cannon (HL1) <- unknown glowing green explosives
Needler (HL1) <- switch from tracking f&f to shotgunning a cloud downrange, keep the fact that whatever material it's made out of explodes in a nonlinear fashion the more of the material is present in an area