The Last Spartan Wiki

Welcome to the The Last Spartan Wiki
The Last Spartan is an Alternate Universe Halo/Mass Effect crossover. After the prologue, a novelization of Halo 3's ending, a turian patrol discovers the remains of the Forward Unto Dawn floating in deep space...131 years after the events of the last game. In a historic moment, the Master Chief is thawed out of his Cryo Pod and awakens to a whole new galaxy, one where humanity has not only made peace with most of the former Covenant races, but has since joined the The Citadel Council. The simplest way to describe this crossover is Master Chief put in Commander Shepard's boots, and for such a simple premise, it is awesome. While initially nonplussed about some decisions humanity has made about joining the Citadel races, Spartan-117 and Cortana both overcome their culture shock while the former grudgingly overcomes decades of wartime xenophobia to secure humanity's place in the galaxy...by becoming a Spectre. But all is not well in the galaxy, for Saren Arterius launches an assault on the human colony of Eden Prime in search of a powerful artifact, and while the Master Chief is unable to prevent him from using it nonetheless finds himself on a manhunt across the galaxy.

Other Sources
For further reading on the canon of Halo and Mass Effect, these other wiki's are kinda good. (Seriously check'em out.)
 * Halo Nation
 * Mass Effect Wiki

Also it has it's own tvtropes page.