Of course you can release two versions, but you originally said you weren't going to because it's just stupid to have duplicate releases. What would aggravate me is if you ignore the OS version and praise the pirate one as the "only" one.

I really do think you should make the first 2-4 levels available as "demo" levels, though. Then anyone who has pirated the game knows what they are missing, and they can get the full one. They'll still get to experience it, and they'll notice your work, but just not fully unless they buy it the full retail version of Halo.

This really is as stupid of a decision as it would be for a developer to make their game using DirectX 8 so they can support Windows 95 instead of using DirectX 9, 10, or 11.

It would be smartest to have one version and to do it right.