We're partially in the mood of the original track, progressing to a more menacing mood, then also more “action”.
Perhaps the track should be renamed “underground - epic final boss” ^^' By the end, the track has taken us pretty far from the start, and maybe a little too far from the theme, but the progression is coherent and very nice to follow, with a classic (but effective) “wave” structure: we build up to a small climax, then drop back down to almost the same level as the beginning. Climb to a new climax, higher than the previous one, and drop back to zero, etc... I like it ^^'