Text from HaloWaypoint:
Halo: Spartan Assault is coming to the Xbox One and Xbox 360 this December with a new online Co-op mode that brings the Flood into the fray. But with new content comes new achievements, and below you’ll find the achievement lists for Xbox One and Xbox 360. We’ve broken up the Gamerscore points for which achievements are new to Halo: Spartan Assault, which are exclusive to the Xbox One version, and the original Halo: Spartan Assault achievements from the Windows 8/Windows Phone version making their way over to the console versions.
For additional information including videos, screenshots and more, check out the official Halo: Spartan Assault page.
(Click to make bigger)
And in case you need/want to know the old ones, here are those too.
No word yet on the cost and when EXACTLY this will release, other than sometime this December.
-Sal