Well there are a couple of ways I interpret this topic.
Hard to get back to due to the age of the game? Like how game design has changed or improved so much over the years that older or clunky mechanics really stand out? This can be a slight issue, but I'm pretty good at getting into a 'retro' mindset and therefore enjoying the game as if I was playing it in its own time.
Getting back into a mid-game save on a game you haven't played in a long time. This one is a killer for me. If I don't stick with a game and shelve it for a long while, I lose most of my memories of it, so I have no idea where to go or what to do next. It's just easier to start completely over, but I usually don't do that either. It takes me many play sessions to get my bearings and try to continue.