Great game I like the idea of playing. I think I won the round we played ;-)
Sometimes the game is a bit monotonous. Maybe you could add a feature like
slow builing of boxes. The player can stop building a box, but if he does the box will be destroyed. So he must deciede if he shoots or builds boxes...

And make the ki a little bit better, so that they go into the area if they can and don't continue destroying boxes...
Another point is the running. In our round you saw that I could run away from the enemy's. Make the player slower or something like this, but at the moment the player can run and run and run and the enemy's don't hit him...

I hope you will add the lan feature, because I think the game will be great on lan-party's

Mfg, Martek