It's typical for the use cases for different actions to overlap a bit in Forged in the Dark games. The intent is to clarify the goal of a player and gets the conversation between player and GM going. Some examples:
- a character giving covering fire to their crew sounds more like shoot than battle or murder, since the intent is to shoot a lot
- a character wanting to beat someone to death sounds more like murder than battle, since the intent is to kill them not fight them
- a character wanting to snipe at a target in order to disable it sounds more like shoot than murder, since they aren't wanting to kill anything
- a character fighting their way through a crowd sounds more like battle than murder, since again they don't want to kill anything, they just want to clear a path, but if they want to kill as many people as possible, that would be murder instead
Being a big sci-fi universe with a bit of crunch to it, it made sense to have more actions than a typical Forged in the Dark game, to capture the breadth of what player character could do, and give them more decisions on how to spend their action points and specialize their characters. Someone with lots of points in murder is a very different vibe than someone with a lot of dots in battle or shoot.
Also in such a grimdark world, 'murder' felt like too good of a keyword to pass up.
Hope that helps!