I have an alien race which has developed fundamentally different from humans. Whereas humans are divided by political borders and have been fighting each other in wars since the dawn of time, my aliens developed in a more unified and peaceful manner. They focused mainly on scientific advancement. The first violent skirmish on their planet didn't occur until after they were capable of aviation - and by this time, they had bombs and rockets. It wasn't until they ventured into interstellar travel that they were exposed to actual warfare (to this point a foreign concept to them). In deep space, almost all engagements could be handled by long-range weapons - like cannons, rockets/missiles, artillery, etc. This means that they have never been engaged in the type of close-range soldier-to-soldier combat that we, as humans, are all too familiar with - and thus means that they have never developed a weapon comparable to human guns. Long story short, a variety of events results in this alien race invading Earth. They catch a surprise, however, when they learn that they have no effective means to defend their outposts against extremely-close-range attacks by humans armed with guns (about the only thing the aliens could do is bomb themselves). This leads the alien occupation forces on Earth to adopt the use of human-made firearms for defensive purposes. After studying the design of human firearms, the aliens develop their own guns based on human designs. The keyword here is "based on human designs" - these aliens have never seen anything like a gun until they came to Earth. Therefore, their guns must operate in a similar fashion to, and must exhibit an obvious lineage from, the human firearms from which they were developed. So just how "different" would these guns be? Do you think they would still require an explosive charge to fire a round - or might it be something else, like electromagnetic propulsion? How might the alien guns compare to their human ancestors - advantages/disadvantages? What limitations might the alien guns have that human guns do not - or vice-versa? Discuss!