Activision owns the rights to Arcanum, but Tim Cain has the source code. Cain even said recently that he tried compiling Arcanum for win10 /11 and it worked flawlessly.
People geeking out cause of the bioshock look / feels but this, from the inxile website hypes me beyond everything: "The project is led by Game Director Chad Moore and Principal Designer Jason Anderson, who just happen to have created one of the greatest steampunk RPGs of all time—Arcanum"