Please don't decorate ceilings with ridges and crap unless it is deliberately intended for strategic purposes.
For example, certain parts of Nexus6 with ridges on the ceiling are very very difficult to traverse quickly as a Marauder or Dragoon, and are simply vomit inducing as a dretch.
If it is intended to retard alien movement for some sort of ultimate balance, fine. If it just happens to look pretty, please just don't, or at least leave a clear path through them.
Thank you.