As someone who has lived rather isolated for long stretches, I think the one thing that helps fight feeling isolated is to find your joy and practice it. My joy is in creative outlets. When I'm alone, I sing, woodwork, cook new recipes, garden [indoors or out], sew. If I had a large indoor space I'd probably practice slacklining, aerial arts, tumbling, parkour, climbing. And then there's the computer, where I can create music and endless programs, websites. I haven't even touched on painting, drawing, playing music. And all that can be supplemented by podcasts, music, movies/TV, reading, chores, working out. There's really so much to do indoors if you can cultivate a creative mindset.
A single game of Factorio can take a long time. Mine usually take around 100 hours.
The craving to (tweak|move|refactor|grow) the base for certain personality types that are richly represented on HN can mean you can spend hundreds more on it too.
I think a lot of those physical things you suggested, like parkour and climbing, would be extremely risky because the last thing you'd want is to injure yourself in the middle of an Antarctic winter.
