https://store.steampowered.com/app/1...the_Righteous/ This game released yesterday and has a pretty central focus on transformation.
One of the main features of the game is the Mythic Path system, which allows the player to achieve demigodhood as a lich, angel, dragon, demon and several others. Most if not all of the paths have a transformation towards the end of the game.
It seems that there are also incremental changes to the player character's appearance along the way, it's not just like a model swap at the end. I've seen players with horns and tails and wings and different color skin.