I like the bio / gas idea. Think of this: Your ship is flying along when an armada of evil ships approaches. You launch your lone roofus bomb and it detonates, spreading some sort of agent all over the screen. After a few seconds, the little lights on those evil ships start to flicker and go out, then they just sort of power down or start dropping helplessly, smashing into the planet or whatever below.
You should call it a roofus bomb because I think the name and smothered alilen pilots in dropping ships are funny.
--
"Del Duio has received 0 trophies. Click here to see them all."
"To be a true ninja you must first pick the most stealthy of our assorted combat suits. Might I suggest the bright neon orange?"
DXF Games, coming next: Hasslevania 2- This Space for Rent!