As mentioned above, in order to have enough energy for playing, a cat must get plenty of sleep. It is generally not difficult to find a comfortable place to curl up. Any place a human likes to sit is good, especially if it contrasts with your fur color. If it's in a sunbeam or near a heating duct or radiator, so much the better. Of course, good places also exist outdoors, but have the disadvantages of being seasonal and dependent on current and previous weather conditions such as rain.
Open windows are a good compromise.