Imhotep
On Obelisk side D, can you build a height that another player is already working on?
A forum reply reads the expansion's select-a-free-space rule this way, and no designer ruling is cited.
- JonBob · Community · 2022-08-22
No. You can only choose a free space, and heights are first come, first served, so if another player is working on that height you must pick a different one.