Here are some random thoughts of mine:

Vibe is a bit reminiscent of early/mid 90's metal ballads, mainly Metallica's Nothing Else Matters and a little pit of Pantera's This Love.

There's definitely the nucleus there for a strong song. I recently caught History of The Eagles and they detailed the process of how they wrote Hotel California. Don Felder sent Don Henley and Glen Frey a cassette with a bunch of riffs and chord progressions for song ideas. One in particular (that was actually lifted from a Jethro Tull song, but that's another story )caught their ear, and that turned into the grandiose Hotel California.

So what you have there, like what Felder sent Henley and Frey, is a good starting point.

But where do you go from there? Vocals? Instrumental?

One thing I would strive for is giving the song a palpable sense of building. It's a bit stagnant harmonically, as the e minor - G Major goes on for quite a while before changing. Nothing wrong with that; in fact it can actually build tension for when the chords ultimately change. Just approach the eventual change of chord to D Major as a climax/point of arrival.

One way of doing this is to add one chord - an A of some sort (power chord or A7)just before the D to 'set it up.'

It would look something like this.

em / Gm / em / GM-A7

And you could get the sense of building by gradually making the texture thicker. Maybe keep just one distorted guitar when it first comes in, then double track when it gets to the D; stuff like that.

Good work!