Although I do not collect this range and I probably would pass on the release, I do love older forts and fortifications. These comment is directed at all Manufacturers, when developing fort, fortifications or earthworks, PLEASE NO VISIBLE SEAMS!!!
Often the individual pieces are sculpted and painted very well, but when assembled there is a broad, ugly seam where the adjacent pieces touch. It would be relatively simply to develop one of the pieces to have an small overlap element and the second piece to slip under the overlap obscuring the seam. Some decorative element, a simple board, wood framing, a drain pipe - just anything to cover the visible seam. If you leave these broad ugly seams when the piece is assembled, I will pass on the piece and release.
When developing the fort walls, there will be some who will want "add" even more additional wall pieces. Again, please design for that and again NO SEAMS if an additional wall is placed. This would allow for changing from a square to a longer rectangle configuration. In terms of display, it is hard to add both length and width, but relatively ease to add if only the length is increased. For display and space, easy to go from 18 inches x 18 inches to 36 inches by 18 inches.
The fort has to be designed to actually accept the figures and the figure bases. Designing a fort where figure bases do not fit comfortably and securely on the walls is not uncommon. I purposely place and inner lip of fort walls to "lower" the chance a figure can be knocked off. When possible, stairs should have broad secure landings. Reference the below photo.