Pets or animals, in general, can be stroked, washed and/or fed due to player action. With the advent of touchscreen and motion controls support, this extended to the player being able to interact with these creatures more directly in console and portable titles alike. This made games which are dedicated petting simulations more viable.
See Groping Mechanic for when the target is specifically humanoid.
See the Can You Pet The Dog Twitter page for an ongoing catalogue.