Ghouls'n Ghosts was one of the most influential games I ever played. It has even guided, in some ways, my aesthetic when it comes to the very modus of Paintery Itself.
Here is a piece I wrote about this game, Hosted and Compiled by the venerable Mike Bevan and his Destroy all Monsters!.
And I present, once again, Ghasts'N Ghouls.
Of course, I have played with many other ideas...