"Upon the release of our 10th Anniversary Update, there will be two versions of KI:

The Killer Instinct Base Game will be FREE TO PLAY on all platforms: Xbox consoles (One, Series X|S), Windows PC, and Steam.
The free KI base game will feature one free weekly rotating Fighter and Single-Player, Local, and Ranked modes.
The Killer Instinct Anniversary Edition ($29.99 USD) will include all 29 Fighters, and all Premium Content ever released: the VIP Double XP Booster, holiday accessories, and more.