Halo is a series of top selling shooter games since 2001. Reach is the latest and the concluding part of Halo series. Halo Reach includes some of the best gameplays. There are a total of 25+ wallpapers you get with this theme.
The Halo Reach Windows 7 theme can be downloaded from Microsoft Official Site here.
This is an official theme pack and hence it can be applied directly by downloading and double clicking it.