I like the first riff. Its kinda cool, but that second riff is sooo boring. Its like the worst Metallica rehash ever. The third riff isn't much different. I'd say definitely develop this further into being a complete song, but listen to it back A LOT more and figure what sounds like cliche, boring stuff you've played before or heard played a million times by others, and get rid of it. Add some lyrics, add some bass, program better drums, mix the drums punchier, then submit the full song. I hate to be a pessimist, but I just can't stand hearing people submit "parts of songs," or just something they threw together in five minutes to post online. To me that is a cop out from actually dedicating yourself to your music and creating something original and entertaining. You have what sounds like a good ear for music, and based off your previous cover song, you have skills too. So use them and don't waste your listeners time with stuff that that is beneath you. Alternatively, don't call it a song. Maybe a tone sample, but not a song.
Yeh, I'm being critical, but hard criticism is what will make you a better musician.
On the flip side, I like your tone. Tight, but with a hairy edge.
