Halo: Spartan Assault was a Verizon Windows Phone 8 exclusive. It was set to go live today to all carriers though. If you try it from your phone the Marketplace still doesn’t show it. Just hit the web marketplace from any carrier on your Windows Phone 8 and you’ll be good to go. For now the only option is to buy (no trial) but it’s Halo – if you read this far you’re buying it, like I did.
update: Damnit, while I’ve ‘purchased’ it, it doesn’t appear on my phone and hitting ‘reinstall’ on the web doesn’t change that. it isn’t being pushed yet. And yes, I am on Wi-Fi. Anyone get it to work?