A couple major problems.
First of all, changing to Low Quality made almost no difference whatsoever. The game was just as laggy as on High. You need to put in a few Graphics Options, just basic stuff like no death animations (ie twitching severed limbs), no crowd animation (the moving crowd in the arena massively slowed down the game), etc. I understand one of you runs a graphics site, but there need to be ways to tone down the graphics. (8 for graphics because they were so good, they were bad.)
Second, some of the enemies were insanely overpowered on Easy. Even with the lightsaber, the shotgun, and as many grenades as I could afford, I couldn't beat the trio (BPK?) in story mode. The Girl's Uzi barrage took away about a third of my health bar each time, and when The Boy's grenade exploded, it stretched from the bottom of the screen to the top, leaving no room for maneuvering. The Pig wasn't so bad if you had a gun, he would just do a cyclone thing when you got close.
Finally, the 'password'. (This isn't a major problem, just a minor annoyance.) I searched through your site, but couldn't find anything about a password. Does it really exist?
Overall, awesome game. I'm glad someone's bringing back this genre. :) Good luck!