-Back to the Future: The Game - 30th Anniversary Edition (Xbox 360)
-Halo 3: ODST - Master Chief Collection Add-On (Xbox One)
-Halo: Reach - Master Chief Collection Add-On (Xbox One)
-Marathon: Durandal (XBox 360)
-The Walking Dead - The Complete First Season (Xbox One)
I already owned Halo 3: ODST and Halo: Reach on Xbox 360. But the Master Chief add-on editions on XBox One were both under $10 (ODST being only $5), have a visual enhancements, and the achievements give me an excuse to play through them again.
And I've always wanted to play the Marathon games, being a Halo fan and all, but never owned a Mac. I had no idea they made an Xbox 360 version until I stumbled across it in the Xbox Marketplace!