Here we go!
M41A Infantry Pulse Rifle
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The m41a Pulse Rifle is the standard infantry rifle of the Near Future. Much akin to today's assault rifles, it is a good all-around choice in terms of stopping power and ease of use.
The weapon must be held with two hands to fire effectively (pagedown, or click it while in hand). It has a small delay in between each shot so cannot be rapid-fire spammed, so make each shot count. The magazine will eject onto the floor when empty, or you can empty it early by using the verb in the object tab.
Damage: Medium
Calibre: 10mm
Firing Speed: Medium
Magazine: 30 rounds
M39 Submachinegun
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A small, light-calibre sidearm used primarily because of its light weight. Unlike most other weapons it is fired one-handed, and its quick firing rate allows you to unload a full magazine remarkably quickly.
It is best used against lightly- or non-armored xenos, as the low damage output per round will have a very difficult time penetrating thicker exoskeletons.
Damage: Light
Calibre: 9mm
Firing Speed: Fast
Magazine: 30 rounds
M37 Pump Action Shotgun
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A tricky weapon to use effectively, it nevertheless has great damage output. It fires only high-calibre slugs which can do excellent damage to any target.
The M37 slugs are also armor piercing, giving a significant bonus against heavily armored threats such as Praetorians, Ravagers, and Queens. However, it is vastly ineffective at distances more than about 5 tiles due to reduced accuracy. To pump the shotgun, either shift-click or use the verb in object tab. To reload it, drag a box of shells into your sprite, then take each shell and insert it in the shotgun. You will have to pump it once before firing, after a reload.
Damage: Medium-Heavy
Calibre: 12 gauge
Firing Speed: Slow
Capacity: 8 shells
M4A3 Service Pistol
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The small, but useful M4A3 is a good holdout pistol or emergency weapon. It is the only firearm that can be stored in any sized container, including boxes or pockets. It has surprisingly decent stopping power for its compact size and every marine should carry one as a backup sidearm. It is near useless against any armored threats, but its quick firing rate can put a lot of bullets into a target very fast.
Damage: Light
Calibre: .45
Firing Speed: Medium-Fast
Magazine: 12 rounds
.44 Magnum Peacemaker
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While of actually smaller caliber than the Service Pistol, the .44 Magnum Peacemaker has higher quality manufacture and extremely heavy, dense custom-sized ammunition. It does excellent damage for a one-handed weapon, but is bulkier than the service pistol and cannot be stored in pockets.
The 44 magnum is reloaded using an 8-round revolver clip, rather than a magazine.
Damage: Medium
Calibre: .44 Magnum
Firing Speed: Medium
Capacity: 8 Rounds
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Those are the weapons commonly available to Marines. None of them should be unfamiliar to people. Now let's get to the good stuff!
M42C Scout Rifle
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The M42C is the latest in a line of heavy sniper rifles designed by Armat Systems. It's rare for a squad to be outfitted with one, but they can cause serious havoc. Like the M41, it has an auto-discharging magazine, but its low capacity means each shot has to count.
The M42C also comes equipped with an extremely useful long-range scope, which can be activated in the Object tab. Like other large weapons, it must be wielded in two hands before it can be fired, but the scope can be activated with it held more casually.
In addition, unlike all other firearms, the M42C has inverted accuracy falloff due to range-- at close ranges it's much more likely to miss than at far distant ranges. Originally an anti-tank rifle, it is one of the primary weapons to use against large, heavily armored targets like Praetorians, Ravagers, and Queens.
Damage: Very Heavy
Calibre: .50 Armor Piercing
Firing Speed: Extremely Slow
Capacity: 6 rounds
M92 Grenade Launcher
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The M92 is an interesting weapon, a midpoint between the heavier rocket launchers and the projectile shotguns. It is very versatile, and being one-handed allows it to be fired while being protected by, for example, a riot shield. To reload it, simply insert a grenade. The M92 is a significant advancement over its predecessors in that it has an auto-lock mechanism which stops it from being accidently fired at anything that's close range. In addition, its 5-chamber revolver-style grenade housing allows all 5 grenades to be fired in rapid succession, quickly laying down a barrage of devastation.
It can also be loaded down with custom-built grenades from the Research Department.
Damage: Variable (Explosive, gas, fragmentation, smoke)
Calibre: Grenade
Firing Speed: Fast
Capacity: 5 grenades
M83 SADAR
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The M83 is a reloadable rocket launching system availably, like the other heavy weapons, only to Specialists. It carries the heaviest ordinance available to any Marine, which comes in two varieties -- high explosive rockets and armor piercing. The primary explodes immediately on contact, sending shrapnel and fiery death in all directions, while the armor piercing rockets have a heavy tungsten warhead and timing mechanism, allowing it to penetrate into armored targets before detonating.
HE rockets are best used against lightly-armored or tightly packed enemies, so the high yield can deal the most damage. The AP rockets do very little explosive damage, but directly hitting a target with one does massive damage. The main downside of the M82 is its rarity of ammunition -- unlike the grenade launcher, its source of shells is very limited.
Damage: Extreme (HE, AP)
Calibre: Rockets!
Firing Speed: Slow
Capacity: 1 rocket
M56 Smartgun System
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The most complicated piece of equipment in the marine's arsenal is also one of the most devastating. While lacking true "smart" capability in tracking targets, it nevertheless contains extremely complex targeting algorithms that allow the gun to nudge the aim away from friendlies, ensuring the smartgunner will never commit friendly fire. It has a very high capacity, does excellent damage, and doesn't require the user to carry a stack of ammo magazines. It can be fired very quickly, allowing the competent Smartgunner to lay down a wide field of suppressive fire in a short amount of time.
The Smartgun comes in 4 seperate pieces: The M56 gun, Combat Harness, Headpiece, and Powerpack.
The Harness is a lighter version of the standard Marine combat armor with numerous attachments to keep the M56 gun stabilized. It is required to even pick the gun up at all. The headpiece is an optional part of the toolkit, though a very useful one -- it uses infrared sensors to illuminate the local area regardless of ambient light levels. And finally, the Powerpack is both a high-capacity power cell storage and contains spare belt ammunition for the M56. To reload in the field, simply click the powerpack icon that appears in the top left corner of the screen. Once it's completely dry, however, the powerpack cannot be refilled and a new one must be acquired.
Damage: High
Calibre: 28mm
Firing Speed: Fast
Capacity: 50 rounds
Powerpack Capacity: +250 rounds, 1000-charge powercell
M240 Incinerator Unit
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The M240 is a medium-capacity, standalone flamethrower with fuel tank and igniter system. When ignited (activate in hand to open the menu), it allows the wielder to spray out a line of superheated liquid plasma, ensuring the area is well-dosed in flames. The intense heat, however, will not spread, instead being limited to the area of the burning plasma, similar to burning White Phosphorous.
The amount of plasma exhaled can be changed -- at low intensity, the M240 can be used to clear burnable obstacles without wasting much fuel, while at high intensity it can deal extremely high amounts of damage to anyone unfortunate enough to be caught in the flames. It deals a high degree of initial damage to anyone caught in the primary blast, and then burns anyone who remains standing in the resulting fire. Spare plasma fuel cells are strongly recommended, and they can be refilled only at the plasma canisters in Engineering.
Damage: Extreme + medium Damage Over Time
Firing Speed: Fast
Capacity: 1050 kPa plasma tank (max), 315 kPa (default)
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Hope this helps! Expect more added here when and if they're finished!