Bored kitty

I'm looking for some advice. It seems that especially lately my cat Barnaby is bored and maybe lonely at times. I live alone and he is the only cat in the house. I work nearly 60 hours a week at times and I am busy doing other things as well where I am not at home.

The problem is that when I attempt to play with him, he quickly loses interest in the toys. He has no interest in balls. The fuzzy mice he chews the tails off and then lets them sit. The string on a stick is about 50/50 and the feathers on a stick which he loved when I first bought, does very little for him now. He will sit in front of the fireplace and look up at the mantle (where I keep the 2 stick toys) and beg. When I take the toy down, he will take some interest in it for maybe a minute, then he will just lazily lay on the floor. But if I put the toy away and walk away he will get up and chase after my feet. It's like he doesn't want to play with the toy but doesn't want me to put it away either. If I leave the toy alone with him he will chew on it and destroy it.

I have thought about getting another cat (kitten) but I am so afraid of the risk of changing Barnaby's behavior. He is such a sweet cat and I don't want to make him feel betrayed or do anything to change the way he is. He has had litterbox evasion problems in the past and I am also afraid that another cat using his box will cause problems because he is very fussy about the smell of the litterbox.

I would like to have another cat but what if I bring one home and it causes complete chaos with Barnaby? Like I said, I am gone quite a bit and I feel it would be hard to introduce a new kitten to the household.

What do you think? Any suggestions about the toys or another cat?