Dear mates, maybe I should explain why such question raised.
I play The World of Terrifying Silence mod for Terror from the Deep, written by Nord. It is great, however compared to vanila TFTD has features:
- labs accommodate only 25 scientists instead of 50. So to get usual number of scientists(100) total four facilities are required instead of two.
- all alien stuff like implanters, cloning, learning arrays, bah corpses even, whose in vanila was sold immediately freeing store space in the mod have some important usage as ingredient for something, so it should be kept for later use - and keeping them requires storage space. MUCH of storage space.
- I've read on forum about aliens can bombard bases, so point defense systems + repellent shield also seems to become mandatory.
- there are also plenty of new facilities, some of them are mandatory to progress research like Bionic Laboratory, or really nice to have like Naval Control Center. Sadly, due to increased usage of available space for stores they simply can't be afforded, in main base at least.
- also, you've taken away possibility to freely move facilities around the grid some time ago, or at least made the feature hidden.
All the above causes that vanila basescape grid 6x6, perfect for vanila Ufo:Enemy Unknown and Terror from the Deep 20 years ago becomes too small nowadays - so some way to accommodate that new stuff/required increased quantities of old one, be it 2nd basescape floor or bigger grid, should be provided. More than 8 bases are nice, however the issue is too few space in single base.
I have learned in this thread some facilities now can be build over to get increased space, and sure I can use .rul files to say create storage spaces with 10k capacity, but that's not the point. The point is to have base mechanics fit to game contents, and currently that balance has been a bit off.
So 2nd basescape floor solves that perfectly, and also fit to theme - alien bases have multiple floors, so can we. This also can create another strategic planning layer as now some facilities may be set as available to build only on specific floor.