well, i'm not really a video game/even castlevania music geek, but i did start looking stuff up when i came across the awesome rendition of bloody tears from the "dracula battle perfect selection" track, while looking for some iron maiden.
that said, i'm somewhat of a bass player myself, never professionally, just playing around when i feel like it. from what i've learned and what i know, bass playing was never meant to be what les claypool(primus) or victor wooten make it. just like drumming was never meant to be what john bonham(led zeppelin) makes it. both instruments were designed soley for keeping the beat of a song, but of course someone will come along that practices the heck out of it, and makes better than average use of it.
so try to understand, simply for the sake of keeping a beat, a re-usable bassline, and even a 1 note bassline, either making a galloping type sound, like iron maiden often makes use of, or hitting the note and letting it ring for 4 seconds before hitting it again, is perfectly acceptable.