Make level 7 of double height

[Mikolaj]

Not sure how this should manifest, except a slight difference in curvature change rate. Anyway, this is needed for the zoo and park rooms, with trees, etc.

[Mikolaj]

BTW, not necessarily level 7 and possibly more than one, especially until the game matches the plot and the latter is updated.

Perhaps mark the double height by the presence of many trees and get rid of tress (and room definitions that contain them) on other levels. Already a couple of levels are open and with trees, so these may be good candidates. Also, perhaps the final battle with animals can be moved to a shallower level, possibly the zoo level with trees, but it would need to be a side-level (when they are implemented) to keep the battle optional.