Hey, I'm glad you enjoyed the game! I currently have no active plans for an expansion, even though I have some ideas that I might play around with in the future. I am developing another game in somewhat similar taste to this however so follow me to get notified when that drops.
Hey! Yeah I love these types of megastructure games as well, the game I am currently making is sort of like that, but more focused on fast paced FPS. I can't reveal much but it somewhat similar to a megastructure but in a lighter and more vibrant tone as to the Concrete Catacombs depressive and abandoned feel.