My cat is a stray who adopted us, slowly over time. He's sweet but v timid. If you go to stroke him, he'll cower like he expects to be hit. If I try to play with him even with a bit of string, he gets scared and runs away! I've seen him play with animals outside, maybe a mouse or a frog and think he's killed birds but just not playing indoors! Maybe he just never learnt how to do it?