Now this is a badass boss battle theme! It features the Commodore C64 SID Chip and has a quite classic approach: You have some mean, stomping bass drum, which keeps a steady pulse in a high tempo. A lead Pulse/Saw voice plays an fast ostinato between C and C# (minor implied), creating a discomforting feeling, as if something big is going down, as if something is hunting the player. Soon a bass voice follows, which in itsself sounds wicked. In the B-part of the song, it calms down a bit, but invokes an threatening feeling and introduces another arp-y synth. Finally some real melody steps in, but the corresponding arp makes sure that it feels „wrong“ in a way. After that there’s a grand finale, introducing even more chromaticism, while the rhythm stays ridig. Finally, the song begins to loop.
As already hinted, the song would make a great addition to any boss battles, fro slimy alien monsters in a Contra-like game, to the creepy Arch-Demon in an JRPG-style game.