Oh gotcha I missed the parts where only the spaceman can traverse! Cool. Your game felt pretty deep for the jam. I loved the feel. Again seriously consider continuing to work on this game. I feel like theres an awesome space adventure game hiding in this game.
I recommend you check out RayFire, it'll do the pre-chunking of models for you. Its a bit hard to use and learn, but once you do it works well enough and has some good performance. It'll occasionally go on sale for around $100.