And we have backround! (Still need more though...)
I like where this is heading.
I like your series y'know. And why? Because you're trying! Because you're trying with both the visual delivery and the story. ALPHA tries harder with visuals it seems to me. You actually have characters with motivations and conflicts. That's the basis of a good story. Perhaps you do not succeed in all aspects - as portraying drama with sprites is hard as hell anyways, but that doesn't stop you from trying!
The problems that are there though:
Woody accepts Chases story a bit too fast. Also he does not seem very shaken from the fact that he has seen the destruction of his city for more than a couple of seconds. It focuses too soon on only Chase.
Also, Chase seems to be the only one with background here. Nice flashbacks though - though I still think dramatic orchestral music would have suited better than those beats.
Mark was a nice touch. His character also makes sense, even! Which is a lot for a flash series. I hope you bring him back even again! Don't forget your characters. The fight still could have been even harder for our heroes though... but that is just my taste.
Overall, though, the series keeps getting better.