I've had best results with either mixing kibbles with canned food or soaking kibbles with chicken broth (no sodium added). You might also think about adding some nutritional supplements like probiotics and enzymes. I got mine from
toplinepet.com They're in a powder form and I just add a little sprinkle on their kibbles/canned food.
As for toys... did he like the squeaky toys? How big/small is he? Does he like puzzle toys?