I've enjoyed what bits I have saw so far of Omega man but Omega man wasn't truly original either. It's based loosely of the book from 1954 titled I am Legend. From seeing the opening scenes of The Omega Man it appears as the creators of the I am Legend movie was giving a nod at The Omega man IIRC Heston is tearing around in a blue Mustang in the opening scene after crashing some other car. Smith was doing the same in a Red Mustang. Neither would be a reference to the book though since Neville swore by driving only Willys.