When I was 17 (20 years agao) I never listened to metal, but then I played Carmageddon 2 on pc and it had some metal music as BGM. I liked it and took the CDROM to work to play the music and a collegue reckognized it as a small obscure rockband called Iron Maiden hahaha. I bought me an album, and started listning to other bands (like the relatively well known band metallica :p) and trough the years I evolved my metal taste into more brutal subgenres like black metal and symphonic bands like Rhapsody of fire.
TL;DR metal in videogames was actually the reason I love the genre today
That said; there are loads of good covers on youtube. Some guys play multiple tunes and are quite proficient at it. Some harder to find ones were good too (I saw a good cover of Breagers Castle from Gargoyles quest once in bad quality, but well played).
but if you are into Videogame tunes turned into metal you should check out the band Vomitron and their albums 'No NES for the wicked 1&2'. it got some quality classic videogame music made metal, including, but not limited to, Double Dragon, Zelda 1 and 2, Castlevania.
Videogames that have good Metal soundtracks are quite rare imho, usually its just some rhythm guitar with a synthersizer and computer generated drums. if those count; I really digged Doom's soundtrack, and there was some BGM in tekken 5, SCII and Devil may cry that were pretty good... but wasn't really metal... just a rhythm guitar to guide some electronic or symphonic track.
Also fun metal-videogame fact: Insanely twisted shadow planet (indie game) featured music from Dimmu Borgir, but it featured orchestral versions, not the full metal songs. it was pretty good though (Progenies of the great apocalypse was on it, and I love that song).