Killer Instinct has swapped out its first free playable character as of a new 675MB update. Since launch in November, Jago has been freely available to test out. Now, it's Sabrewulf.
The full list of patch notes from developer Double Helix can be viewed at the link below. There's balancing and general improvements, like a forced pause when player two's controller is removed and the display of rank-up/rank-down notifications for both players at the start of a match.
As someone who hasn't been playing the game and can't comment on specific gameplay tweaks with any real confidence, I will say it's nice to see those nasty "Chosen One" Achievements reduced. Previously, players needed to 2,000 matches completed with each character. That number is now a more sane 200 wins, which should be great news for completionists.