Cool idea, but I think the aliens need a bit of work...until I read your description I couldn't tell the aliens were actually aliens. Also, the crowd needs some details that show they're rocking, not screaming in horror as they're attacked.
I agree - good effort, worth a 3. I love the buildings, but the aliens look sort of like a Rorschach test. This Chicagoan would love getting rocked by some rock n roll aliens, however.
p.s. My First Submission and not my last!
-Terra