Hear, hear! Some works such as Gate and ZnT are wasted on their authors, who just stumbled onto an awesome setting only to misuse it grievously. Kudos to all fic authors who took these jewels and polished them to what they could have been.
The Saderan Empire isn't defeated yet. Remember, they're still Romans at their core and they are more than willing to send men into the meatgrinder if it means victory. There is a saying in Rome that means 'you aren't defeated until you accept defeat', and that is something that makes Rome different than the rest of the Classical world. They could have a fifth of their male population dead and then go 'we'll be back next year' (which is exactly what happened in the 2nd Punic War after Canne, which had Hannabil -the man that practically brought Rome to its knees- go 'what' in response).
The thing is, this is for the setup for the real meat, the post-war politics and nation-building. Also it isn't a railgun but it is a naval rifle repurposed into an AA piece repurposed into an anti-tank gun.
Thing is, the usual MO had been open the Gate long enough to set a reasonable breeding population through, close it, and then wait a while. If whatever is beyond the gate is too dangerous (they can walk back and forth through the gate like mortals), they can simply retreat and shut it before anything comes over. What the Sadarian gods didn't expect that the Sadarians themselves effectively putting a doorstop onto the Gates or the Old One (aka the actual Admin) coming back home as it were.
The Dark Elves showing up would be for non-god related reasons as rumors of the Men in Green's selflessness spread.
[raises eyebrow]
... I then recommend either watching Backyard Baseball videos on Youtube or grabbing ScummVM, grabbing the Backyard Baseball images from trusted abandonware sites or straight from their disks (you only need no more than 5 files to get them to work) and learn that way.
The reason I know quite a bit of baseball is because of Backyard Baseball as it actually helps you understand quite a bit about baseball.
First, stop trying to make me spoil the fic. [/semi-serious] Second, she'll need to understand how GATE!Earth and Iron Pact!Earth's musical theory evolved before putting her understanding of music/magic relations to it, which means she'll be digging through their combined musical canon. Everyone should know how deep and broad humanity's musical canon is. If you don't/can't comprehend how broad and deep humanity's musical canon is, then let me do a comparison: GATE! and Iron Pact!Earth's musical canon is like a large and deep ocean in just how much there is to go through just due to just how much time and resources were put into music (to give an example, Germany has so many composers and musicians to its credit thanks in part to the various German states having a cultural arms race between each other) in general, Falmart -due to having less time and resources put to it alongside interference by the Saldarian pantheon- in comparison is like the Mediterranean. Amala is going to understand it, it'll just take time just due to how much she has to dig through. It's like our warrior bunny squad digging through the library who has to dig through a lot of stuff to get a good understanding of everything.