Halo Wars

I got Halo Wars when it came out, and I didn't really feel the right amount of excitement. For a game like Halo Wars, I feel like I should be tearing into it. But for some reason, I feel kind of subdued about it. It might be because I'm worried about the replay value. I actually got the Limited Edition version, so I sunk about 75 dollars into it. Naturally, I feel like I should get the bang for the buck, you know? I mean, when I play it, I enjoy it. But I'm wondering how much play I'll get out of it.
I expect that I'd be supah excited about it if I had Xbox Live, because one of the best features of it is the multiplayer. But not only is it 40 bucks a month for Xbox Live, but we don't have a way to connect it to my internet. I am a mac user, so we can't use the wireless port thing that came with the Xbox, and it's on a seperate floor from my computer, so linking it with wires is out of the question. We would have to blow a hundred dollars on a bridge, plus pay $50 a year. Not that it wouldn't be worth it. It's just, the money factor is.... relatively large.
I currently own, for my Xbox 360:
Halo 2
Halo 3
Halo Wars
Bioshock
Lego Indiana Jones/Kung Fu Panda (Came with it)
And my brother just ordered Left 4 Dead

I want to get:
Mass Effect
Resident Evil 5
Braid
Singularity