I'm pretty sure they're just offshoots of hardcore, but the rock type of hardcore (like, hardcore punk) rather than the 90s electronic rave kind of hardcore. That's the case with grindcore anyway, never heard of nightcore but it sounds depraved.
I don't really know what you call this subgenre of trance. Is it even such a thing? Probably not. But these songs seem almost reflective in their nature.