This one got my attention, as I'm a lifelong hardcore kid, (which metalcore, naturally is an offshoot of), but there's 2 areas just from the description that bug me. A, instrumental metalcore? Wait, what? Now granted, the drumming in metalcore can get pretty interesting & elaborate, but the guitar riffs tend to really be more to just carry the song along & aside from the occasional breakdown, musically, metalcore music structure acts as a bed for the vocals, meaning it doesn't really work without the vocals. I mean for example, Look at Zao's "The fear is what keeps us here". Phenomenal drumming, Great guitar & base composition, but strip out Dan's vocals & lyrics & it get's kinda dull & repetative.
Also Fame & drugs? Now, I'm guessing that the writer is from outside the US, So maybe the culture there is a bit different, but here, Nah. I mean Hatebreed is likely the most famous band in the genre, but one thing that followed MOST metalcore bands into that subgenre from it's roots in hardcore, (which in turn came from hardcore's roots in early 80's hardcore punk like Black Flag, Minor Threat, the Circle Jerks, etc..), Is that ethos of DIY grounded ethics. Chasing fame isn't really a thing in those genres. As for drugs, Man oh man oh Chavez. While there are some outliers where drugs become a thing, (such as Rob from Ramallah / Blood for blood), drugs are more shunned in those communities than anything else. I mean half of the scene is straight up straight edge. & for most that aren't edge, they don't really go much further than smoking or a bit of drinking. Not really a lot of drug fueled "Rock star" like partying in that scene. Might make more sense to switch it to the early 90's & change the genre to grunge, or maybe the 80's & switch it to hair metal or something, because that fits that "rock star" theme better.
Like I said though, maybe the metalcore scene is different where the author comes from. But if the game is based in NY, then you gotta make it true to the NY scene. & when you look at bands like Sick of it all, Madball, Agnostic Front, etc... That ain't them. lol