It's not just Ensemble Studios' strategy take on the Halo universe we're giving away in our Halo Wars comp. You could also win the no-longer-available-in-shops Halo 3 branded Xbox 360 console and the Legendary Edition of Halo 3, including that Spartan cat helmet up there. All you need do is leave your Halo haiku in the comments of the original post.
But remember, a haiku contains three lines of 5, 7 and 5 syllables. Good luck!