Killer Instinct, rotating out Jago for Sabrewulf in the free-to-play version of the game. If you're rocking the free-to-play version and want to go back to Jago, you'll have to drop $5 to unlock him.
The patch also includes a host of general fixes – like squashing a bug that would erase player data when signing in with Kinect and updating the ranking system to allow for quicker progression and fewer demerits for losing online matches. There's also a few fixes for some previously unblockable conditions, which you can read about in the full, in-depth patch notes over on the Double Helix forums.
Killer Instinct was a launch game for Microsoft's Xbox One console. While the current roster is only comprised of six fighters, Double Helix has promised at least two more: Spinal is expected to appear sometime this month, while Fulgore will join the cast in March. Following all of Double Helix's planned season one content, an Arcade mode will be added to the game.