I think that looks quite good and very playable! I really like how you have made a large pool of modular parts, like ramps and stairs, that work with most (maybe all?) of the box buildings.
The only thing I would expect to see more of is doors and windows on the buildings, but I don’t think that’s really a problem for this kind of individual structure- those often have fewer doors and windows than residential or commercial buildings. Adding doors and windows probably would limit how the build parts can be placed, so leaving them off makes sense, especially if the buildings are mainly for blocking line of sight and providing elevated ground in your games.