(Just some of them)
Weapon attachments are effectively small items like any other item that, when you click on a weapon that can accept it, will (after a short delay to field-modify it), be attached to that item. It automagically updates the weapon's overlays so it looks cool, we don't have to make multiple sprites for each gun which makes things a LOT faster and easier for us behind the scenes.
Each attachable has a variety of modifications it can do to guns -- from simply changing its stats, to doing complex stuff like acting as a flashlight or firing different projectiles. You might be surprised by the number of subtle effects adding an attachable can do-- primarily you'll see attachables changing the weapon's accuracy, as most things add a certain amount of weight which unbalances the weapon (as in, The bullet narrowly misses the runner!, that's accuracy in effect). Removing attachables from a weapon is easy, but you have to strip ALL attachables at the same time, not just pick and choose. You'll see a new verb in your Object pane-> 'Field Strip Weapon'. After a short delay, if you don't move or drop the weapon, it'll dump all current attachments on the floor and you can re-attach whatever you need at your leisure.
All weapons have 3 attachable slots: rail, muzzle, and underbarrel. Some weapons only take attachments in certain slots, and some weapons have none at all, so don't expect to be able to put a masterkey shotgun onto an M37 combat shotgun. Heh. You know you'd try it.
Here's a list of what we've got so far, subject to change:
Suppressor
Mounted on: Muzzle
Changes weapon to Silenced. This greatly reduces the firing sound, and removes the text message about firing the gun. Slightly reduces accuracy. Mounts on: M41, M42C Scout Rifle, M39, and M4A3 Pistol.
Flashlight
Mounted on: Rail
Allows use of the Toggle Weapon Light verb. Unlike other attachments, you can build your own mountable flashlight by screwdrivering a normal flashlight, and change it back by screwdrivering the attachable itself. Mounts on M41, M37, M4A3, and M39. No drawbacks.
Bayonet
Mounted on: Muzzle
Triples the normal melee damage of a gun (usually 10->30 brute), at a slight penalty to accuracy. Also changes the weapon's attack verb, just for flavor. Mountable on M41 and M37 only.
Red Dot Sight
Mounted on: Rail
GREATLY increases weapon accuracy. Has no drawbacks. Can be mounted on: M41, M39, M37, and M4A3.
Forward Magazine Grip
Mounted on: Underbarrel
Contains a second magazine and auxiliary components. Doubles magazine size and increases accuracy, but makes one-handed weapons become two handed and slightly reduces projectile damage due to replacing some of the machined parts with experimental ones. Mounted on: M41, M37, M39, and M42C Scout.
Gyroscopic Stabilizer
Mounted on: Underbarrel
A computerized rig that automatically adjusts the weapon's balance on the fly. Changes two handed weapons to one-handed, but at the cost of accuracy - there's only so much it can do. Also causes the weapon to have recoil (screen shake) when firing, and replaces much of the magazine well, giving half magazine size. Mounts on: M41, M37, M42C Scout.
Underbarrel Grenade Launcher
Mounted on: Underbarrel
A two-shot grenade launcher that can be toggled with a verb in the Object tab. Fires grenades, comes standard with 2 standard issue frag grenades. Mounted on: M41. Can be reloaded by detaching the launcher, and clicking on it with grenades.
Masterkey Shotgun
Mounted on: Underbarrel
A 4-shell shotgun, works the same as the grenade launcher. Click verb, fire. Like the grenade launcher it also requires you to field strip the weapon, then reload the masterkey manually. Only mounts on M41.
Mini Flamethrower
Mounted on: Underbarrel
A small-tank flamethrower, with a range of 2 tiles. It has a VERY small tank and cannot be refilled, only replaced. Mounts only on M41.
