if playing Killer Instinct offline is important to you do not get the definitive edition through the microsoft store. the reason is because there is a certification issue that when you turn off your internet; you will only be left with Jago and who ever the free character is (Orchid is also free but you gotta work for her in shadow lord). despite what people think this not an intentional design choice, alot of people think that nothing is available unless you connect to the internet. and the reason i know that it’s not true and this is a bug is when you fill the shadow lord bar to %9 you unlock the retro jago outfit, i’m at %4 and can still access the retro jago outfit plus whether it’s jago or the free character i can still use the gold skin for each character. if you want the windows 10 version but also want to play it offline download the free version; navigate to the in game store and buy which ever characters or bundles you want and install them this will allow you to play those characters offline. and if you already messed up and bought the game through the microsoft store and are beyond the point of being able to get a refund (like me) relax man all hope is not lost.
make a new account on your computer and on the microsoft store
install the base KI don't worry you don't have to do another 50GB install just a 30 - 40MB install
buy which ever characters or bundles you want then install them.