Just needs a few touch-ups but it's great need an Infinite mode instead of 20mins of survival...
Possibly a High-scores board.
And a map editor, multiplayer would be EPIC add all of theese and you have a game of the year on your hands! (plus more weapons)
 "ShellShock Live"){kind=icon}
 "Zombies in the Shadow - 20 to die"){kind=icon}
 "The Sandbox"){kind=icon}