What’s RSD?

This is it. It’s your free time, OP. Don’t push yourself so hard and put these expectations on yourself to conform to how you’re “supposed” to enjoy things. In your daily life, you probably already have enough pressure to conform and have to put energy into working around your ADHD.
Just play a game for as long as you’re having fun. If it’s not fun anymore, whatever. It’s okay to move on to something else if you enjoy that more. If you really want to know how the story ends, you can always look it up or watch some clips.