FAQ 1: Why the Organism troops don't use energy weapons.
Although ray guns have been a popular trope for alien armies for more decades than I've lived, they do have serious issues. The really big one is that annoying atmosphere. Lasers and other energy weapons just don't work well with them. Aurora shows this with the protection an atmosphere grants a planet against 'death from above'. There are ways round this mind. Careful choice of laser frequencies or the right kind of particle beam can result in a ray gun that works well (theoretically) in an atmosphere.
But there is a problem that is often glossed over. Space going 'marines' need to be able to fight in any atmosphere. From hard vacuum, through the merest trace, to super dense ones. Worse, the composition can be very variable. It's bad enough crafting a laser that will work in our own atmosphere, let alone one that's a bit denser but has a few more percent CO2 in it! Now remember you need to fight anywhere!
Neutral particle beams are viable in a vacuum, but awful in an atmosphere. Charged particle can work in an atmosphere, but are tricky in a vacuum. Even 'rainbow' lasers, which Aurora doesn't seem to have at present are tricky in an atmosphere.
So I decided (long ago) against ray guns, unless you can 'force jacket' them. Yes, force jacketing is a handwave, but it does do the job and has at least a veneer of plausibility.
The Organism were always going to use bullets. A high velocity chunk of metal has always been a good way to harm your opponent, and they nearly always work. Depending on the technology level, you can have conventional, caseless, ETC, binary propellant, gauss or, as the implied technology supports it, grav. Aren't those grav rifles nasty eh? (grin)
