to pick up this thread: I thought I'd contribute a little bit. My concerns over copyright issues remain, but I guess as long as the game requires the original files, adding stuff as mods should be fine...
here's my version of the stun grenade. I'm not sure about the "stun gas" thing, because I don't remember reading anything about it being a gas. if it was a gas, why did it stun sectopods and cyberdiscs? and why did it use elerium? why wasn't there a lingering effect (like purple stun-smoke)? I always think of it as some kind of neural disruption effect, which would also affect the cybernetics of the advanced cybernetic terror units, but not the simple x-com tanks.
so I think the stun grenade should be more like a stun bomb with a direct fuse: