In the U.S., visual aspects of software are generally copyrightable. Check out the Pac-Man v. KC Munkin case from 1982. There are several others. www.copyrightcodex.com/infringement/16-infringement-substantial-similarity/software-copyright-infringement#Pac-Man_v_KC_Munchkin

But when "visual" includes GUI, there's less copyright protection (because user interface elements are functional). Check out the Apple v. Microsoft case from 1994 as an example.

I'm not sure what the equivalent UK law would be.