Pretty cool! For things that could be added (beside the turret that's already been mentioned) is making it a darker grey or green and getting some minifigure parts from brickarms to make an actual lego spartan minifigure. :)
Your Warthog is quite good.
If you want to now the rules of my table-top game have a look at my Halo multiplayer test game - 2 on 2.
The basics are explained there ... but it was an earlier stage there ... Since then I made some changes and developed some new stuff, but it might be only a guide ... everybody can create own rules. You only have to take the time to think about all that stuff. I'm working on it for nearly a year, now. It becomes playable by the time^^.